VQ Oil Analysis and Info
 

Here is a great read that I found over at My350z.com. This probably should be a sticky!

Props to Resolute at my350z.com for putting this together :biggthumpup:

This thread is a collection of Used Oil Analysis (UOA) results and data to help owners of VQ35DE powered vehicles decide which oil brands and weights are best for their engine’s needs. The first part of this thread is laid out in a Q&A style format. I update this section frequently with current data, and all new questions are placed in the Q&A for reference. So, please read through this page before posting a question, as it’s probably already been answered. The remaining pages after the Q&A contain contribution from members, many of whom have paid for their own UOA and selflessly shared the results. This data is added to the first page and kept current, and I would like to thank everyone who has contributed for the benefit of the Z community.

So what’s the best engine oil to use in my VQ35DE?
There’s not one “best” oil. There are several oils to pick from and, depending on your needs, I recommend:
Amsoil 0W-30- A new formulation has come out in 2007 that performs as good as, or even better than, the old one. An excellent oil in terms of protection and stability for oil change intervals up to 10k miles. It is now a thinner oil than before, so I don’t recommend it for the FI crowd or track days.
Pennzoil Platinum 10W-30- This oil has the second best wear numbers of any oil tested so far, with three different test results all reporting the same findings. It’s viscosity and TBN numbers mean it’s not the best choice for oil change intervals over 3k miles or track days, though. Great for the daily driver in warmer climates.
Schaeffer’s 7000 5W-30- The best overall wear results. This oil has low shearing and is good for longer than average oil change intervals. A great choice for a 5W-30, but I don’t recommend it for track days or FI. Possibly the best oil for the daily driver.
Mobil1 0W-40- A thicker oil with really good to average wear results combine to make it a versatile oil for the daily driver and those who do track days as well. Will hold up well for extended oil change intervals and can be used in any climate.
Castrol GTX 5W-30- A conventional oil that outperforms a lot of synthetics, it is inexpensive but an excellent choice for the daily driver using regular oil change intervals.
Castrol Syntec 5W-30- This formulation produces some of the best wear numbers tested so far. Stable viscosity for extended oil changes up to 6k miles.

How did you come to these conclusions?
I base my decision strictly on the Used Oil Analysis(UOA) results. The oils with the lowest numbers of metal particles in the oil (especially lead, copper, and chromium), and the most stable viscosities are the best. The data is in a comparison chart attached below for people to draw their own conclusions if they wish.

What is a Used Oil Analysis (UOA), and where/how/why is it done?
It is an analysis of used engine oil performed at a lab. Customers collect some of their used oil, usually during an oil change, and send it in to the lab to be analyzed. Two of the most popular testing labs are:
http://www.blackstone-labs.com/
http://www.dysonanalysis.com/index.html
After running several tests on the oil sample sent to them, the lab sends a data sheet back to the customer that shows the condition of the oil. The oil condition highlights issues such as engine wear by showing how much of certain metals wore off from inside the engine and into the oil. An oil that protects well will have low numbers of metal particles in it. A UOA will also show how much the oil has broken down with use, and highlight the presence of any dirt, anti-freeze, sludge or fuel in the oil. Having a UOA performed will reveal the properties and effectiveness of a particular oil, as well as any problems within the engine that may be developing.

How do I read the attached UOA Comparison Charts?
The name and weight of each oil tested is at the top of the comparison charts. The column below it shows the mileage on the sample, followed by any amount of make-up oil added during the change interval. This is important to look at when comparing oils, as an oil that had just 1,000 miles on it when tested will obviously fare better than an oil that had 9,000 miles on it when tested, even if it is not really a better oil. The next part (The Grey Section) of the column contains the elements found in the used oil, recorded in parts per million. This reflects the type and amount of metals that were worn off of engine parts, and the amount of additives in the oil. The bottom of the column (The Red Section) shows the oil viscosity and TBN.

Where do the traces of metals come from, and how do they indicate engine wear?
The most common sources of metals in your used oil that come from engine wear are listed below. These metals come off of different parts of your engine during operation. Your oil protects the surfaces of your engine from wear, but some oils do a better job of others. Oils that have high numbers of these metals did a poor job of protecting the engine’s surfaces from wearing down with use. So look for an oil that shows lower numbers of these elements, that means the oil did a better job of protecting these areas from wear:
Iron: Wear of cylinder liner, valve and gear train, oil pump, timing chain, rust in system
Chromium: Piston ring wear
Copper: Bearings and bushings wear
Lead: Bearing corrosion and wear
Aluminum: Piston and piston thrust bearing wear, internal surfaces of the engine block
Silver & Tin: Wear of bearings

Where do the other elements come from, and do they indicate engine wear?
The only other element to look for in low numbers, in addition to the wear metals listed above, is silicon. High silicon could mean a bad air or oil filter is not trapping dirt. The other trace elements are usually part of an additive package that oils use. It doesn’t matter if an oil has a large or small amount of these other elements in terms of engine wear. Looking at the numbers of the other elements can be useful in determining if a manufacturer has changed their formula, or to see what type of additives they use. The most common other elements found in an oil sample and what they commonly indicate are:
Silicon: usually dirt, sometimes part of an oil’s chemistry
Molybdenum: anti-wear additive and friction reducer
Boron: anti-wear additive and friction reducer
Calcium: common additive with many functions
Magnesium: common additive with many functions
Phosphorous: anti-wear additive and friction reducer, shear stabilizer
Zinc: anti-wear additive and friction reducer, shear stabilizer

What do the viscosity numbers mean, and how do I read them?
The viscosity numbers are from a specific test to determine the viscosity of an oil at a given temperature, as measured in cSt (centistrokes). The reason some numbers are in deg F and others are in deg C is because different labs do different tests to measure viscosity. The details aren’t really important. All you need is to look at the numbers and realize a higher number means a thicker oil at operating temperature, and a lower number means a thinner oil at operating temperature. A higher or lower number is neither good or bad in and of itself, it is merely a measure of the oil’s viscosity. It may be surprising to see how some oils are thinner than others, despite being the same weight.

Are higher or lower TBN numbers better, and why don’t all the oil results have a TBN number?
The TBN (Total Base Number) is an indication of how much of the base stock was left in the oil to fight acids that build up as a result of oil oxidation. All engine oils break down over time and with wear. The result is an accumulation of acids in the oil. These acids are what forms sludge. The oil’s base stock and the additives in the oil work together to help prevent sludge from forming. The TBN is a measure of how well the formualtion is working to fight sludge and acid build-up. A high TBN means there is more base than acid in the oil. A lower TBN number means more acids formed over time than in an oil with a higher TBN and the same mileage. It is a good indication of how robust the oil is with use. A high TBN is the best indication of whether or not an oil is good for extended oil change intervals. It usually costs extra to get a TBN test done, so not all of the samples have a TBN value.

What makes you think these UOA results from other VQ35 engines are indicative to how well an oil will work in my own VQ35?
To be absolutely certain of what works the best for your engine and how you drive, you would need to do your own UOA. However, the variance from one engine to another is very small if it is the same engine type. Each sample is from a VQ35DE, and different drivers living in different climates have submitted UOA results that show almost identical values for the same oil. Unless the engine is FI, raced, or a built block, the trends will be the same for each oil. It is the trends and tendencies for some oils to outperform others that are important, not the specific numbers themselves. In other words, your own results might show a few wear numbers higher or lower than the results here, but an oil that shows low wear compared to other oils in the comparison charts will still show lower wear than the other oils in your own engine UOA. Only those oils with low wear results are on the recommended list and are therefore a good bet to use.

I use (insert brand name here) and my engine runs fine, and/or is used by my favorite racing team, and/or is advertised as the best, and/or is proven to be great oil for some other engine- how come it’s not recommended?
First, do you have a UOA to share from your engine using your favorite oil? Maybe it is a great oil for the VQ35 and no one has posted a UOA of it yet, so please be the first. If there is already a UOA posted on your favorite oil and it sucks, then keep swearing by it if you must- but I won’t recommend an oil with bad UOA results. If you haven’t done a UOA, then what makes you think it’s such a great oil? Any API certified oil will keep your engine running, so just because it hasn’t seized your engine doesn’t mean it’s protecting better or worse than another oil. Subjective remarks like the “feel” of the engine, dyno results with a particular oil, and biased advertising do not indicate better protection than another oil. Racing engines don’t have the same oil needs as a personal car, so don’t assume what works well in racing will be the best for driving to work every day. Finally, what has been shown to work well in one engine does not mean it shows the same performance in another model of engine. I make the decision of which oils to recommend based solely on the VQ35 UOA data. If you would like to see how your oil stacks up, then contact one of the labs mentioned earlier, get a UOA done, and post the results so we’ll have some quantitative data to judge by.

What about my FI and/or built engine, where’s a recommended oil list for that?
Check with your engine builder for a recommended oil to use with your built FI engine. The clearances, materials, contact pressures, and oil pressure in a built engine can be very different than the consistent construction and measures of a stock block. Therefore, the results of the collected UOA’s may not indicate what works best in your built engine like it does for a stock block engine, and you should see what your builder thinks you should use. Even if you are a stock block engine, but FI, your engine’s oil needs are different because of the extra heat involved. A general rule of thumb is to use a thicker oil than you might normally use. A thicker oil has higher film strength and better resistance to shearing under extreme heat, so a good 40 weight oil is a great place to start.

What does the oil weight actually mean?
An oil’s weight refers to it’s measured viscosity at a given temperature. The temperature of the oil is important when measuring it’s viscosity because an oil becomes thinner, or less viscous, when it is heated. Conversely, oil becomes thicker, or more viscous, when it is cooled. Because oil viscosity changes with temperature, an oil’s weight is determined by the measured viscosity at a specific temperature of 100 deg C. The unit of measure is called a centistroke (cSt). The higher the measure of viscosity at 100 deg C in centistrokes (cSt), the higher the oil’s weight. In order for an oil to be considered a 30 weight oil, it must have a viscosity between 9.3 and 12.49 cSt at 100 deg C. A 40 weight oil must have a viscosity between 12.5 and 16.9 cSt at 100 deg C. A 50 weight oil will have a measured viscosity higher than 16.9 cSt at 100 deg C. The chart attached shows the viscosity an oil must be at a given temperature for each oil weight.

So how does that translate into the weight I see printed on the bottle, like 5W-30?
Some oils are straight weight oils, like a straight 30 weight oil. This means the oil is always a 30 weight oil at any given temperature. The oil still thins out with heat, and thickens up as it cools, but at any given temperature it will measure within the specs for a 30 weight oil at that temperature. This is not good for your engine during cold starts or in cold weather, because a 30 weight oil is very thick when it is cold. Thick oils are harder to pump and don’t flow through the engine very quickly to lubricate the internals. This is why cold starting, and driving before the engine reaches operating temperature, places extra wear on the engine’s internals. In order to solve this problem, the oil must be able to flow quickly through the engine and properly lubricate the internals even before operating temperature is reached. The solution is a multi-grade oil. A multi-grade oil is still thicker when it is cold than when hot, but not as thick as a straight weight oil. In the case of a 5W-30, the “5” refers to the oil’s “Winter” weight (hence the “W”). A 5 weight oil is thinner than a 30 weight oil at cold temperatures, and thereby flows easier to properly lubricate the engine. As the engine heats up and reaches operating temperature, the oil thins out- but does not stay a 5 weight oil. It becomes a heavier weight, and in this case, becomes only as thin as a 30 weight oil at operating temperature. Multi-grade oils offer better engine protection than straight weight oils by preventing the oil from becoming too thick when cold, while maintaining a heavier oil weight when hot.

Are the 0W-xx oils too thin for my engine?
As discussed in the previous entry, multi-grade oils are designed to behave like two different oil weights at two different temperatures. Since an oil is thicker with colder temperatures, a lower weight oil flows better, and better protects the engine during start-up since it is easier to pump to critical areas. So, a 0W-xx oil is a better oil for start-up, especially in cold temperatures. When the oil heats up and starts to thin out, it becomes a heavier weight oil just like a 5W-xx or 10W-xx oil would. So, a 0W-xx oil is only a “thinner” oil when it’s cold- where it is a benefit. At operating temperatures, a 0W-30 is the same weight as a 5W or 10W-30, just as a 0W-40 is the same weight as a 15W-40, etc... Therefore, 0W-xx oils tend to be better suited for year-round use in any climate, since they flow better in cold temps but become as thick as any other similar grade oil when hot.

Why are some oils different viscosities for the same weight of oil?
An oil’s hot viscosity must fall within certain limits at a specific temperature of 100 deg C in order to be classified as a 30wt oil, or a 40wt oil, and so forth. Since a 30 weight oil must have a hot viscosity between 9.30 and 12.49 cSt, there is a range of viscosities that a 30wt oil may have in order to be classified as a 30wt oil. Some 30wt oils may be a “thin” 30wt with a hot viscosity closer to 9.3 cSt, while some 30wt oils may be a “thick” 30wt with a hot viscosity closer to 12.49 cSt, but any oil with a viscosity in that range will be a 30wt oil. As an example, Royal Purple 5W-30 has a viscosity of 9.7 cSt @ 100 deg C, while Schaeffer’s 5W-30 has a viscosity of 12 cSt @ 100 deg C. Both oils are 30wt oils since their viscosities lie between 9.3 and 12.49 cSt, and are therefore the same weight (sometimes called oil grade), but Schaeffer’s is physically thicker (more viscous) than the Royal Purple. The same principles apply to any grade of oil. Some 40wt oils will be thicker than other 40wt oils when hot, same for 20wt oils, etc... This also means that a 0W oil like 0W-30 can be a thicker oil than a 5W or 10W-30 when hot, despite being a thinner oil when cold. Attached is a chart that shows what the hot viscosity of the oil must be for each weight when measured at either 100 deg C, or 210 deg F, so you can see how the viscosities of any of the oils tested compare against the maximum and minimum values for each weight.

Is a thicker oil better for engine protection than a thinner one?
Not usually, but sometimes. A thicker oil will have higher film strength than a thinner oil. Thicker oils tend to manage extreme heat better, and as such are good for racing or FI engines. But, thicker oils create more drag in the engine and can cost you some horsepower and fuel efficiency. The general rule of thumb is to use as thin an oil as possible that still offers good protection from engine wear. The only way to see which oils do this is with a UOA.

How do I know which oils are “thick” or “thin” for it’s weight?
There are two ways to see. First, check the bottle of oil you’re considering. Look on the back for the oil’s ratings. An oil that meets ILSAC GF-4 requirements is going to be a thin oil, and good for maintaining high fuel efficiency over oils that don’t meet the requirement. Another rating to check for is the ACEA ratings. Oils that meet ACEA A3 requirement are thicker oils than those not meeting the specification. Also, API SM ratings are going to be thinner oils than those that meet the older SL ratings. Second, check the oil’s viscosity you’re considering against the viscosity chart attached below. You can find out your oil’s viscosity from the manufacturer’s web site. It is listed in cSt @ 100 deg C. Compare this number with the range of each grade on the chart to see if it is high or low for that weight.

What does the HTHS score mean for oils?
If you look at the data for your oil on the manufacturer’s website, you will probably notice an HTHS score along with the viscosity. The HTHS score is the oil’s viscosity at 150 deg C and refers to the oil’s ability to withstand “High Temperature & High Shear” conditions. This is a good indicator of how well an oil will most likely hold up in a F/I engine, especially one with turbos. Higher HTHS numbers are better for extreme protection in such situations, and will also be thicker oils than those with lower HTHS scores.

What does the Viscosity Index of an oil mean?
Manufacturer’s usually list this value along with their viscosity measures. We have already seen that the hot viscosity of an oil is measured at 100 deg C. An oil’s viscosity is commonly measured at 40 deg C as well. This is not the temperature the winter or cold viscosity of a multi-grade oil is measured at, it is simply another temperature that is considered the lower end of the oil’s operating temperature. Not every oil will have an operating temperature of 100 deg C, and since an oil thickens as it cools, it’s important to make sure the oil doesn’t become any thicker than it’s weight allows at the cooler operating temperature. The ability of the oil to stay in it’s weight across the two temperatures is known as the oil’s viscosity index. A higher viscosity index number means the oil better maintains it’s weight across the two operating temperatures. Oils with a higher viscosity index tend to be more stable.

What does a NOACK score mean?
Some manufacturers also report the NOACK scores as well. NOACK is an abbreviation for a test that determines an oil’s susceptibility to burn-off, or volatility. Oils with low NOACK scores lose less of their properties to volatility, keep their original protective qualities longer, and keep oil consumption lower than oils with higher NOACK scores. It can also be an indicator of the base stocks used in an oil.

What are viscosity index improvers or modifiers?
These are chemical additives that increase an oil’s viscosity with heat, to counter-act an oil’s tendency to thin with heat. They are primarily responsible for the ability of some oils to achieve a multi-grade oil weight, such as 5W-30. As apposed to a straight weight oil, such as a straight 30 weight.

What other additives are in an oil, and what do they do?
Engine oil additives are an important piece of the puzzle in understanding how one oil can do a better job protecting an engine than another oil. Most oils have about 10-20 % of their formulation in additives. These additives are what make up an engine oil’s composition above the base stock used. A lot of tribologists attribute an engine oil’s additive package as more important in terms of performance than the base stock. In order to really find which oils and the additives they use work best in the VQ, a UOA must be done- the chemical composition of an oil is too complex to simply guess which oils will work best based on their additives alone. Posted below is a list of the different additives and modifiers used in engine oils to achieve their respective traits. The list is taken straight from Molakule on BITOG with my own notes and abbreviations added for clarity and relevance:

Antifoamants or foam inhibitors (Protective Additive): polymers such as silicone polymers and organic copolymers of the silaxane’s; these create a lens that reduces an air bubble’s surface tension. Some oils high in silicon, such as Motul 300V, might be as a result of this additive.

Antioxidants or oxidation inhibitors (Protective Additive): ZDDP, ZTDC, Moly TDC, Antimony TDC, aromatic amines such as organic tolutriazoles, thiadiazoles, diphenylamines, olefin sulfides, carboxylic acids; decomposes peroxides and terminates free radical reactions. Increases temperature of base oil at which base oil may tend to oxidize. Oxidation of oil promotes sludge particles and increases viscosity. May show up as zinc, phosphorous, and moly on a UOA.

Anti-Wear and Extreme Pressure Additives (Surface Protective Additive):
ZDDP, ZTDC, Moly TDC, Antimony TDC, Organic Sulfur-Phosphorus-Nitrogen compounds, Borates and Borate Esters, Tricresyl Phosphates, amine phostphates, and other phosphate esters, Chlorine compounds, and lead diamylcarbamates, lead and barium naphthenates, sulfurized olefins; protective film interacts at various temperatures and pressures to provide either a plastic interface or to provide a compound which shears at the surface- protecting the metal. May show up as zinc, phosphorous, boron, and moly on a UOA.

Demulsifier (Performance Additive): hydroxyalkyl carboxylic esters, alkenlycarboxylic esters; keeps water separated from lubricant.

Detergents (Surface Protective Additive): metallo-organic compounds of sodium, calcium, magnesium, boron phenolates, phosphates and sulfonates such as alkylbenzene sulfonic acids, alkylphenol sulfides, alkylsalacyclic acids; Lift deposits from surfaces to keep them suspended. May show up as phosphorous, boron, calcium, and magnesium on a UOA.

Dispersants (Surface Protective Additive): Alkylsuccinimides, alkylsuccinic esters (alkenyl succinimides); chemical reaction with sludge and varnish precursors to keep them acid neutralized and to keep them soluble. Detergent-dispersants often are the same chemical or come in compounds to accomplish the combined function(s).

Emulsifiers (Protective Additive): Polyisobutylenesuccinimides, alkenylsuccinate ester/salts. polyester amides, alkyl aminoesters; promotes a stable emulsion or mixture of oil and water.

Friction Modifiers or Friction Reducers (Performance Additive): Organic fatty acids and amides, lard oil, high molecular weight organic phosphorus and phosphoric acid esters such as Tricresyl Phosphates, ZDDP, ZTDC, Moly TDC, Antimony TDC, family of diphenylamines and amides, and olefin sulfides. Reduces coefficient of friction formulated lubricant in the boundary lubrication regime. Some VII’s also provide friction reduction. May show up as phosphorous, boron, zinc, and moly on a UOA.

Metal Deactivator (Protective Additive): ZDDP, ZTDC, Moly TDC, Antimony TDC, family of diphenylamines and amides, and olefin sulfides, heterocyclic sulfur-nitrogen compounds; inhibits corrosive effects of oxygen with metals and decreases metal interaction with oxygen compounds to reduce oxidation of oil. May show up as phosphorous, zinc, and moly on a UOA.

Oxidation Inhibitors (See Antioxidants).

Rust Inhibitor (Surface Protective Additive): Barium sulfonates, amine phosphates, phosphordithioates, sodium thizoles (for coolants)

Pour Point Depressant (Performance Additive): polymethacrylates (PMA’s); reducing wax crystal formation and increases solvency of oil at low temperatures. May be part of VII package.

Seal Swell (Performance Additive): nitriles, specific esters, organic phosphates and aromatic hydrocarbons. Increases volume of elastomeric seals. May show up as phosphorous on a UOA.

Surfactants or Surface Active Agents (Protective Additive): family of diphenylamines and amides; usually part of the antioxidant package. Also provides enhanced friction reduction and allows oils to “climb” or spread on and over surfaces. Decreases but does not destroy surface tension

Viscosity Index Improver or Viscosity Modifier (Performance Additive): Olefin copolymers (OCP’s), hydrogentated styrene-diene copolymers, styrene esters, polymetharylates (PMA’s), mixed alkyl methacrylate-vinyl-pyrrolidines, aminated ethylene propylene, mixed alkylmethacrylate ethylene/propylenes; reduces viscosity change with temperature. Increases viscosity of base oil as temperature rises when base oil tends to thin. Some VII’s may also act as dispersants by incorporating dispersant compounds.

What is an oil’s base stock?
The base stock is the main component an oil is made of, before any additives are incorporated to achieve the final product. Which base stock is used determines how an oil is classified. The primary base stocks are divided into five classification groups for engine oils.

What is a Group 1 base stock, and what oils use it?
It is the group that contains the least refined crude oil and not used in modern engine oils.

What is a Group 2 base stock, and what oils use it?
This is the group that contains non-synthetic engine oils. The base stocks are made from conventional crude oils that have been refined to a point where it meets the standards set by the American Petroleum Institute for engine oil. Some conventional G2 oils perform as well as some synthetic oils because of the excellent additive packages used to fortify the base stock. Such oils (see the Castrol GTX UOA in the comparison charts for an example) are cheaper than synthetic oils and offer excellent engine protection. However, G2 oils typically cannot achieve the same viscosity spread as synthetics, such as an 0W-40 oil weight. They also cannot protect as well as synthetic oils when it comes to severe heat and stress conditions like racing or FI. Also, because they use a base stock that is not as refined as the higher grouped oils, they do not typically have the stability needed for the extended oil change intervals that synthetic oils can achieve. It is important to look at the UOA results of G2 oils and see which have performed well. The better performing G2 oils are a good buy for the owner who does not need an extended oil change interval, or FI, or track use.

What is a Group 3 base stock, and what oils use it?
These oils are made from either a severely processed crude oil, slack wax feedstock, or either one of these blended with a Group 2 base stock. We’ll look at each separately:
1. Severely processed crude oils are known as “hydroisomerized” oils. They have recently been approved to market as a synthetic oil. Hydroisomerized oils have gone through an advanced distillation process to remove undesirable crude hydrocarbons (like wax) from the crude oil base stock. The theory is that since the oil has been so thoroughly distilled, and only the “best” hydrocarbons remain in the oil, that it might as well be a synthetic. “Hydrocracked” oils, as they are commonly called, are the most popular Group 3 base stock. Many companies use them for their synthetic oils, such as Castrol Syntec, Valvoline SynPower, the Motul 6100 “Technosynthese” formulations, Schaeffer’s 7000 line, etc... These oils tend to have NOACK scores 11% or higher for a standard 30 weight oil.
2. Slack Wax Feedstocks are the only Group 3 oils not made from crude. The most popular oils that I know of that use slack wax as a base oil are from Shell. The Rotella T-Syn 5W-40 and their Helix Ultra series use this base stock, as well as some Pennzoil Platinum and Quaker Synthetic oils. These oils are more popular in Europe it seems, and can be difficult to find in the U.S.
3. Synthetic Blends are oils that have a G2 base stock mixed with one of the above G3 synthetic base stocks, or a Group 4 or 5 base stock. An example would be Castrol Syntec Blend, which is a G2 oil blended with a Group 3 hydroisomerized oil. Adding the synthetic base stock helps the oil achieve a better HTHS score or maintain viscosity over the course of an oil change interval that a G2 oil couldn’t do on its own. These oils are slightly cheaper than full synthetic oils. They are becoming less popular now that hydroisomerized oils are now considered “synthetic”.

I’ve heard of Group 3+ oils, what are they?
For even better performance, Group 3 synthetic oils may also be also fortified with fully synthetic oils from groups 4 and 5. Because of the addition of higher end base stocks, these are sometimes referred to as Group 3+ oils. They may also be referred to as a breakdown of their group base stock blend, such as a G3/G4 blend, GIII/IV/V blend, and so on. Amsoil’s XL line of oils are in this category, as are some of Motul’s 8100 series like 8100 X-cess, Pennzoil Platinum, the Eneos economy oils, and there is strong evidence that most of Mobil 1’s line-up are also G3+ oils. G3+ 30-weight oils tend to have NOACK scores around 10% to 13%.

What is a Group 4 base stock, what is a PAO, and what oils use it?
These are oils whose base stocks come from man-made hydrocarbons known as polyalphaolefins, or PAO’s. They are synthesized from ethylene gas, which is a byproduct of refined crude oil. PAO base stocks are prized for their flexibility in making oils with a large viscosity spread that perform well over a long oil change interval and under high stress. PAO oils are also more stable in the presence of water and moisture than Esters. In order to be considered a Group 4 oil, the base stock must contain no oil of a grade below Group 4. They must either be a full PAO base stock, or they may use a PAO base stock combined with an oil from Group 5, such as Esters. Examples include most Amsoil oils, Mobil 1 0W-40, Elf Excellium, Royal Purple, some of Motul’s 8100 line-up, and Eneos’ performance line-up. The high performance of the PAO base stock also lends itself well to high stress and high temperature conditions, such as racing. Many racing oils are some type of Group 4 oil, and typically also work very well for street driven cars that see track use or are running some type of forced induction. Group 4 30wt oils tend to have NOACK scores between 6% and 9%.

What is a Group 5 base stock, and what oils use it?
This group includes Esters, Alkylated Napthalene, cycloaliphatics, silicones, silahydrocarbons, polyalkylene glycols, perfluoroalkylpolyethers, polybutenes, and any other fluids that do not fit in Groups 1-4. Esters and Alkylated Napthalene are the two most common, and we’ll look at each separately:
1. Esters are an aromatic hydrocarbon group found in many fruits and vegetables. They are commonly used as flavoring agents in drinks, and for their smells in perfumes. Esters are defined by the presence of one carbon atom and two oxygen atoms attached to the end of a hydrocarbon molecule. Since we have already seen by now that not all hydrocarbons perform the same (hence the whole need for Group classification), it can be assumed that not all Esters function the same in terms of engine oil. There are some 600 known Esters, and manufacturers have found that some Esters can be synthesized from natural resources and be very stable in extreme heat and stress, such as in a racing engine. The manufacturers that use a Ester base stock are Motul’s 300V racing oil, Redline oils, Mobil 1 Delvac, NEO, Torco, and Silkolene. Most Esters help swell and condition seals, and may be used as an additive in other oils for this reason. Esters also have a polar affinity to most metals, and this allows film strength under zero pressure. Some esters, such as polyolesters, are not hydrolytically stable and are not compatible with elastomer type seals. Most Ester based oils will have NOACK scores around 6% for a 30wt oil.
2. Alkylated Napthalene is a less common base stock. It is a synthsized aromatic hydrocarbon. The Alkyl group is introduced to Napthalene and forms a stable polycyclic structure that can be used to stabilize oxidation in the oil. It is usually not used as a base stock by itself, but as a Group 5 additive to other base stocks. Alkylated napthalene resists heat and oxidation better than mineral oil, PAO, or diester, is hydrolytically stable unlike polyolester, has good additive solvency, and is more elastomer compatibile than esters. However, the napthalene complements rather than replaces the esters. An example would be Mobil 1, which is fortified with the addition of AN to its base stock formulation.

Group 5 oils seem to be the best base stock, why don’t they have good UOA results?
Some Ester based oils perform worse than, or no better than, most Group 2 or 3 oils in the same engine. (See the UOA results of Motul 300V 5W-30 in the comparison chart for an example). One possible culprit is an Ester’s tendency for hydrolysis. As an oil’s base stock is slowly degraded over time by oxidation, the result is more acids in the oil. These acids can break down the Ester into an alcohol and a carboxyl acid. This process is known as Ester Hydrolysis. Hydrolysis is also created by an introduction of water or moisture to the oil. It is not an issue when the engine is running hard for most of its oil change interval, such as in a racing series. This is because there is enough energy in the form of heat to catalyze the reverse reaction, that is, to re-create an Ester from the alcohol and carboxyl acid. For an oil that isn’t changed very often, unlike a racing engine, hydrolysis may be a factor. This is only one theory as to why Ester base stocks sometimes don’t perform better than other oils as seen from UOA’s. Another thought is included in this response from a tribologist in regards to a question of why Redline doesn’t do that well in UOA’s compared to other oils of “lesser” base stock:

The subject of an ester’s performance as an oil in a street driven engine can be controversial, since there is no concrete answer. The fact is, some oils just perform better than others in the same engine. Choose an oil by what gives good results, not by the base stocks used.

Is an ester base oil the best type to use?
My opinion is that high Ester oils are better as a race oil, than a street oil. The real advantage an Ester has over PAO synthetics is shear stability in the face of extreme heat. That benefit is going to be realized best in racing, whereas the typical better performing wear protection of a good PAO in start/stop, short trip, and cold start stress will lend itself best to a street engine. High ester base oils have to rely on the additive package to offset some of the negative aspects of the ester base oil, such as moisture stability and elastomer compatibility issues, where a PAO basestock with additives makes a more street friendly oil. I also think the value of these oils are best realized in twin turbo VQ engines, since they are seeing higher temps, and therefore the most important value for them is an oil’s HTHS score. Esters tend to have the highest. I think for daily-driven 350Z’s, a high Ester oil is a waste of money and not doing any favors for the engine. Of course, as I have already mentioned, a UOA should be the judge over how well an oil performs in your engine for your conditions, not speculation on base stocks.

So what Group of oil is the best?
There is no single group that is the all-around best. It can be helpful to know what the differences in each group are, so that when someone says, “That’s only a G3 oil”, or “I only use Group 5 oils”, you’ll know what they mean. You should also realize by now that one base stock does not guarantee a better oil. There is far more to it. The combinations of proper viscosity, additives used, and the type of base stock are all different for each oil. Some perform under specific circumstances and in specific engines better than others. Check for oil samples that consistantly perform well in the VQ, and then you will see a clearer picture of what works and what doesn’t. Better yet, get your own UOA done and check the reults in your own engine. Keep a running log of each oil you try and see for yourself what works.

Great Info, all in one place!

Stickied for now.:biggthumpup:

wow great info Sean

great write up!!!!!! im actually using eneos 0w-50 rigt now. im probably gonna bring it down to 0w-30 now since it's more economical.

Thank you for this valuable information!
Great research!

That is totally incorrect as exampled on great forums such as Bobistheoilguy forums.

I don't think you're to talk since you don't know the base material of one of the products you actually sell and didn't know most of Mobil 1's synthetics were no longer Group IV based.

Jeff, its not totally incorrect. Steve is just making it out to be totally invalid. I think what he is saying is that what works on one engine will not necessarily work on another engine, and will not show similar numbers because there are too many variables to alter the results. With that said, it doesn't mean that the results from another engine are TOTALLY invalid as a good indicator of a good oil for another similar engine. That is where the flaw in his logic fails him. You can't say an oil is a great oil because it works well in one engine based off a UOA, but you can say it should work well in other similar engines, but testing in the new engine should be performed to confirm those results

But you have to consider his frame of technical reference. He wants to be just that critical BUT doesn't even know the contents of his own products?

Yes, the UOAs could be done with more narrow parameters. BUT for a group of guys sharing info across the world, it's pretty good. Plus we can narrow it down to a particular engine/model and similar mileage. If you see enough results with a common theme, then it's reasonable to come to some reasonable conclusions.

which is why I said he wasn't totally incorrect, he has a point, kind of, but just because something doesn't follow the scientific method to a tee, doesn't mean some type of correlation can't be made. Just by using different oil filters, I bet I could alter the results to a certain extent on the same engine.

Maybe. I don't know how Blackstone etc... measures amount of metal. The filter is going to get to an XX micron level but probably isn't too discriminating.

Blackstone might be using a measurement method that doesn't let what size particles affect their analysis. ie.. measuring % metals that are smaller than xx micron size. ie.. smaller than any filter can handle.