Why go 10w30 when you can go 5w30. Wouldn't 5w30 provide better startup protection while providing the same level of high temperature protection?

2004 Sedan 6MT
Silver/Graphite/Premium/Aero
HuperOptik Ceramic 50
XM
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5W30 is a very thin oil that helps initial flow at startup... during the winter months. However in climates where the temp is always above zero, a thicker oil protects better. I live in FL, initially used 5W30, and my analysis results showed relatively high wear metals. The oil entusiasts over at bob's recommended a thicker oil that would cling better to engine internals, providing more protection between two moving surfaces. In theory the more oil molecules between surfaces, the less friction occurs. So unless you experience subzero temps regularly, 5W30 offers no added protection.


<font color=red>chinee</font color=red>
03.5 G35s

 

chinee

thanks very much for your help. One more thing though. I guess I don;t know what the numbers in the oil weight spec mean. In 5w30, for example, what do the ttwo numbers mean. I understand that they stand for viscosity, and that these oils are multi-weight (?).

I know in airplanes we use 25 or 50 "single" viscosity oils.

Thanks very much

--Gurgen

 

Gurgen

On every bottle of motor oil there is a seal that gives you three pieces of information:
The API service rating
The viscosity grade
"Energy Conserving" indicator (it either is or it isn't)

The API service rating is a two-letter rating that tells you the type of engine the oil is meant for (gasoline or diesel) and the quality level.

The viscosity grade (for example, 5W-30) tells you the oil's thickness, or viscosity. A thin oil has a lower number and flows more easily, while thick oils have a higher number and are more resistant to flow.

Multi-weight oils (such as 10W-30) are a new invention made possible by adding polymers to oil. The polymers allow the oil to have different weights at different temperatures. The first number indicates the viscosity of the oil at a cold temperature, while the second number indicates the viscosity at operating temperature.

At cold temperatures, the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up, the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C, the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot.

04 G35 6MT Coupe
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Thanks very much. So 5w30 is the sae as 10w30 for all intents and purposes if I am looking for good protection in hot conditions. I guess 5w40 would be ideal. Does it exist?

Gurgen

 

What do you guys think about this oil. Do you think this is what I should use in turbo applications?

http://www.amsoil.com/products/aro.htm

 

Multi viscosity oils are one of the great improvements in oils, but they should be chosen wisely. Always use a multi grade with the narrowest span of viscosity that is appropriate for the temperatures you are going to encounter. In the winter base your decision on the lowest temperature you will encounter, in the summer, the highest temperature you expect. The polymers can shear and burn forming deposits that can cause ring sticking and other problems. 10W-40 and 5W-30 require a lot of polymers (synthetics excluded) to achieve that range. This has caused problems in diesel engines, but fewer polymers are better for all engines. The wide viscosity range oils, in general, are more prone to viscosity and thermal breakdown due to the high polymer content. It is the oil that lubricates, not the additives. Oils that can do their job with the fewest additives are the best.

Very few manufactures recommend 10W-40 any more, and some threaten to void warranties if it is used.

04 G35 6MT Coupe
35% Madico smoke tint
CF Hood
Injen Cat-back

 

I'm a big fan of Amsoil full synthetic after reading various independent comparisons over the years. They make good stuff. As far as using a 20W50 oil, I don't think the engine was designed for it. You'd be better off with the basic 5W30. I've used that 20W50 in my Harley (Harley recommends a 20W50, and they've always used dino oils, though now they offer a Harley branded synth).

I had an Audi S4 with the twin turbo, and the recommended oil began as 5W30, either dino or synth. A year later they changed that recommendation to 0W30 year 'round due to better flow at startup and also in cold weather. They also found no difference between the 0W and the 5W for high temp resistence. Kind of interesting, anyway.

jjellyneck

 

So again I ask, why isn't 5w30 better that 10w30? Seems to me that they have the same high temp properties. The 5w30, being a thinner oil at low temp, will protect the engine better on startup, right? As for high temp conditions, the second number in both oils is 30, which to me means that they are esentially the same. And when it comes down to it, I would think that most engines have relatively the same operating temp regardless of outside air temp (unless your WOT in Death Valley or something). It is my understanding that every vehicle's cooling system designed to keep the engine at a specified temp which is determined by engineers, based on fuel economy, type of oil to be used, expansion of parts, etc... Someone tell me if I am way off.

2004 Sedan 6MT
Silver/Graphite/Premium/Aero
HuperOptik Ceramic 50/Clear Corners/XM Radio
Z-Tube/Stillen High Flow Airbox/Grounding Kit

 

That's odd. I know on all my previous own BMWs from V6 to V8 were all recommend to use 20w50 thru dealers. If I remember correctly the owner manual recommended 15w50. I have switch to 10w40 when it reach 70,000 miles. The difference I felt is that I lost WOT acceleration from mid to top end when I switch to 10w40 but startup and regular driving is a lot smoother. Also, with 10w40 my fuel economy is better too. Maybe this is why 330 is able to catch up and pass us in the top end. I love my G35 but I do feel the mid and top end acceleration at WOT still lacks the kicks from BMWs.

~ GT-R the Ultimate Driving Machine ~
- 2004 G35 Ivory Pearl/Black Leather
- Auto/Nav/Premium/Sports/Aero
- 6 wire grounding kit

 

<blockquote><font class="small">In reply to:</font><hr>

So again I ask, why isn't 5w30 better that 10w30?

<hr></blockquote>

Actually this question is tougher to answer than you think. When selecting a multigrade oil, generally it is better to have as narrow a range as possible... specifically why... I can't answer accurately enough. At a minimum, I can tell you that many oil enthusiasts change their viscousities with the season, using thinner when cold and thicker when warm.

If this topic truly interests you, visit bobistheoilguy.com and read for a few weeks. The members over there are very level-headed and helpful.. and do not deride newbies. I've garnered enough knowledge to be comfortable with my oil choice and change interval, even though the results I've gotten may not be perfect (yet). Especially Gugen, you're thinking about running FI; if you want a recommendation, I say check out bob's site, and spring for at least a couple of UOAs when you do the installation.


<font color=red>chinee</font color=red>
03.5 G35s

 

For those of you in SoCal, I can tell you that the Infiniti dealer I go to automatically uses the 10-30. We do not need the 5-30 here. It never gets cold enough.
I am going to go to Mobile 1 10-30 on my next oil change (12K miles).

 

I've been using Amsoil 0w-30 ever since my first oil change and i couldn't be happier. Its a damn good oil. In california, this 0w-30 is awesome. Look into it. Pretty much every amsoil person you speak to will suggest this 0w-30 oil over the 5w-30. It is a better oil.

I am using it along with the amsoil sdf-13 filter. Great combo.

 

No doubt that Amsoil is generally regarded as a superior oil, but here's some costs to consider:

If you use Castrol GTX @ $1.50/qt and a $6.00 Purolator Premium Plus oil filter, an oil change will cost you $14.31 (every 3750 miles)
Using Mobil 1 @ $4/qt with the same filter will cost about $27.56 a change.(every 7500 miles)
Amsoil @ $8/qt, with 2 filters(filter change @7500 miles), will run you $55.12 a change.(every 15,000 miles).

Those intervals seem to be appropriate for the oils above, so driving 30K miles a year, my costs for oil changes will be:
Castrol - $114.48
Mobil1 - $110.24
Amsoil - $110.24

Wow... when I started this message I expected that the yearly cost for M1 would be higher than GTX, and even higher when using Amsoil. Looks like I got myself a new hobby... I may be buying Amsoil for my next change and perform oil analyses every 5K.


<font color=red>chinee</font color=red>
03.5 G35s

 

I buy the Amsoil 0W30 for $6.25 per quart from a local dealer.

jjellyneck