I've been searching high and low for the Castrol Syntec 0w30 German oil, only to find that apparently it's not sold in the US anymore. However, I did find 0w40 Castrol oil, made in Germany on the bottle, etc etc (no longer branded Syntec though, just Edge). At $9.49 per quart it ain't cheap, but if it's as good as the old stuff I'm gonna use it.

Anybody have any experience with this oil? All I can find is information from the BMW guys, but that's a whole different animal of a motor. Our manual says 10w40 is allowed, but I've also heard that Castrol German tends to be a bit more viscous than the weight suggests.

 

Personally I wouldn't ever change viscosity unless you know exactly what you're doing and how it affects the motor.

These engines use oil pressure for maintaining timing chain tension as well as driving the cam actuators. Changing viscosity affects oil pressure which directly affects the hydraulic force those components deliver.

Use too thin of oil and you suffer from a lack of pressure and insufficient actuation, use too thin of oil and you risk starving the rotating components of oil flow. They need oil to be moving at a specific rate to ensure proper cooling and lubrication and dual-overhead cam engines require a LOT of oil to quickly make it to the top of the heads especially on cold starts.

For racing applications where you're generating a LOT more heat (or larger bearing clearances on an engine build) you use higher viscosity oils like w40 or even w50 in some applications, our engine uses oil squirters on the underside of the pistons so the oil is subjected to a LOT of extra heat which is mitigated through the use of an oil cooler but it's still washing around in the crankcase as VERY hot oil until it makes it's way to the cooler. Typically you adjust viscosity based on changes to oil pressure, as the pressure drops in a racing environment you use a higher viscosity to compensate but it's also largely determined by the clearances of your bearings. This motor uses pretty tight clearances but not nearly tight enough to EVER warrant the use of a zero viscosity oil like the 0w30 you're looking at.

There's a lot of misinformation and bullshit surrounding viscosity selection, a lot of opinion and even more apples-to-oranges comparisons like "it works great in this german high performance engine so it must be great for my engine too!"

Another issue is oil shearing, basically as the oil is compressed tightly the molecule is ripped apart, in dual overhead cam engines this happens a LOT more because of the multiple cams riding on the lifter buckets. Your viscosity changes as you put miles on it so if you're running 0w30 then after 3000 miles it's become even thinner. This isn't nearly as big of an issue for synthetic oil because it's a much smaller molecule to begin with but it still shears to a degree.

Anything that moves causes shearing, the oil in your crank bearings (minimal shear), rod bearings (extreme shear), cam bearings (minimal shear), cam lifter buckets (high shear), oil pump (high shear), etc. As force is applied it squishes the oil inside the bearing to one side and that very thin protective film is what protects the metal components so it's never a direct metal-on-metal contact. There should theoretically always be a very thin layer of oil molecules between the two moving parts to create a lubricating film that only measures a couple thousandths of an inch and there's an engineered gap a couple dozen thousandths of an inch so there is a small volume of oil that fills the gap, enough to provide lubrication and ensure a constant flow of new oil but not enough room for the moving parts to generate enough momentum to slam into each other and create excessive damage.

One of the best things you can do to ensure the longevity of a motor is to use a "high mileage" engine oil from DAY ONE on the motor. Just as the EPA has it's filthy claws into all other areas of your powertrain forcing manufacturers to do things like suck dirty exhaust air or crankcase vapors back into the intake manifold to burn them a second time they have also forced manufacturers to chemically alter oil so it doesn't cause as much "damage" to catalytic converters. When the oil has been pressed down to the point the molecules shear the only protection that remains is an ultra thin layer of viscosity improvers and additives. This is literally the ONLY thing keeping metal from directly touching metal once the oil molecule shears but our oil has undergone a couple of changes mandated by the American Petroleum Institute (basically the EPA's way of controlling our oil). They grade the oil using a GL-# or GF-# designator and it's basically a way of keeping track of what additives were added to the oil (a fancy way of measuring how much phosphorus and zinc is in it), newer GL/GF oils like GF-5 and GF-6 have SUBSTANTIALLY changed/reduced additives to reduce emissions even further. They offer protection to the motor but in a completely different way and in almost every case in a WORSE way, especially on motors designed for higher cold-start viscosities.

Most automotive manufacturers, because they're under the iron heel of SOME environmental agency around the globe, has no choice but to meet the modern emissions standards so they design their engines to be able to survive the inferior quality oil that they're required to use, so you end up with engines that are engineered to run on 0w20 and stuff like that. They literally CANNOT use looser bearing tolerances because once the oil shears there isn't nearly the protective film left on the part and the engine would wear out quickly, they have to keep ultra-tight tolerances just to make the engine last.

Why would you want to run that oil in an engine never designed for it??? You're not just risking damage to the engine you're practically GUARANTEEING IT!

I don't know all the in's and out's of the engineering that goes on for an engine at the design table, but I know that the team of engineers spent YEARS developing the engine to work with a specific set of lubricants. I also know that for the most part the newer class of lubricants doesn't work as well as the older ones because of governmental emissions control.

Here's the loophole though, an oil that's deemed to be "higher mileage" does NOT have to obey the same GL/GF classifications! The manufacturer's are free to use the old (better) additive levels which provides better protection for the most part. You will need to do your own research to see how much phosphorus and zinc (look for a measurement of ZDDP in the oil spec sheet).

Also of note, on any new vehicle, if you are somehow caught using an older oil it can technically void your warranty because the higher zinc/phosphate levels do cause slightly more wear on the catalytic converter but they provide significantly better protection for the critical rotating components.

The VQ35DE was engineered to use GF-3 oil (also GF-1 and 2 but only for the sake of obsolescence). I would never try to run a GF-4 or GF-5 oil in that engine, EVER.

 

After a tiny bit of research it looks like the Castrol 0w30 is only sold under the Castrol EDGE lineup which meets ILSAC (european version of API) GF-5 requirements.

I would definitely not ever use that oil in my G35.

 

Lots of good information unfortunately don't have the time to fully digest as I'm literally walking to said car I'll be changing oil on now. Few things while I do though:

You said you would never change viscosity from the manual, but Nissan says 10w40 is ok in the manual. Wouldn't a 0w40 be the same but flow even better on cold starts? I was under the impression that oils like the Mobile 1 0w40 consistently got the best wear ratings for the VQ35DE. My block has 150k, so I'm looking to treat her as nicely as possible as she has a slight drinking problem.

This 0w40 German Castrol I've got has an API SN/CF (it's an A3/BE rating European formula, for what that's worth).

 

Also, you said that 0w30 would never be needed, as the tolerances aren't tight enough; wouldn't that solely affect cold starts, and even then reach the top of the motor faster? My knowledge (or lack thereof) is based simply on UOA of VQ35DE's, where (original, apparently not nowadays) Mobil 1 0w40 European Formula and the Castrol Syntec 0w30 German/European Formula (are those even the same thing?) were the long reigning kings.

 

Lower viscosity = lower oil pressure (edit: lower than the viscosity it was engineered for). One of the many engineering variables is sizing the gear of the oil pump for a particular viscosity.

There are no good UOA statistics on this engine, blackstone doesn't have the compiled data available to the public and any attempts that folks on forums have had in compiling data has resulted in fewer than 10 tests per oil type. There's absolutely no way that can be taken as a valid comparison because nothing is known about the condition of the engine, the driving conditions, the length of time it was in the crankcase, etc.

5w-30 is the preferred year-round viscosity but 10w30 is fine if you live in a hotter environment, 10w40 is fine if ambient temp is consistently above 100F.

EDIT: Yes these numbers are all in the FSM and probably the owners manual as well.

Typically I run 5w-30(edit) in the winter because we regularly get down to zero degrees, summer I run 10w-40 because we have at least a month of 100+ temps here in southeastern washington state.

 

I'm NW WA, so it's basically +20 deg low end and -15 deg high end temps here. I imagine 0w40, while ok for hot days, would be a bit too thin for startups in the summer? I NEVER start driving until I see the needle move off the peg a few millimeters; is 0w weight still considered too thin for that?

I might just go back to 5w30 Pennzoil Platinum HM. I think I had to do maybe one quart additional over 3500 miles, while 5w30 HM Valvoline has been two quarts in the same time (mostly city though), so it's been my best result so far, just ahead of 0w40 Mobil 1 and decently far ahead of 5w30 Castrol Edge. I was hoping German Castrol (0w30 or 0w40, 0w40 especially as it's available locally) would work well and burn a bit less, but I'm not willing to take that jump unless someone else already has.

EDIT: From what I'm reading here, Nissan wants minimum API SL, so at least the 0w40 German Castrol fulfills that at API SN. Biggest problem seems to be that 0w, especially considering my relatively mild climate in the PNW (my engine was pretty smooth and quiet with Mobil 0w40, but I lived in Moscow Idaho where it could be 30 degrees in late March. Worked well in the summer though).

 

OMG, just use the viscosity Nissan recommends...they know what works best in their engines! This isn't rocket science, don't make it so! If your intention is to use a great quality synthetic try AMSOIL 5w/30, you can achieve 10+ lbs. oil pressure at 3K rpm!
Gary

 

Yeah over on the west side I would probably just run 5w-30 or maaaaaaybe 10w-30. Over here in the Dry Shitties it's substantially hotter in the summer so I usually run 10w-30 or 10w-40(edit)for my summer oil.

The thing I'd look for is product information reports from manufacturers that list EXACTLY how much zinc and phosphorus is in the oil, here's a copy of the one from Mobile1

https://mobiloil.com/~/media/amer/us...pecs-guide.pdf

Valvoline is what I've switched to this year and I've been really happy with the VR1 series oil they make. I've been running 10w-30 and have only burned MAYBE 1/2 qt across 3k miles and usually I'd be getting pretty close to the 2 qt mark by that point. Something to keep in mind about zinc/phosphorus is that MORE IS NOT ALWAYS BETTER. You can find some really high ZDDP oils out there pushing like 2500ppm for zinc/phosphorus but those high levels will cause premature catalytic converter failure (probably only get 100k out of the cats before they die horribly). I chose the Valvoline VR1 conventional because it's listed as 1400/1300ppm which will mean my cats will probably not see 200k miles but I'm ok with that.

Here's the valvoline sheet for the VR1 conventional, the fully synthetic VR1 is like 1100/1100ppm I think but I know from experience that this motor drinks synthetic pretty heavily so I didn't even bother trying it out.

https://sharena21.springcm.com/Publi...2-ac162d889bd1

For reference, any of your modern GL-5 oils are required to not exceed 800ppm

 

Almost all Amsoil Signature is GL-5 and thus low ZDDP, I wouldn't bother with it if you want the engine to last under harsh conditions, but there is ONE exception. Amsoil makes an amazing 5w-30 that's marketed for diesel applications but carries the API SN+ badge that would be an excellent choice for the G35. Here's a link to the product information sheet, it's listed as the "Series 3000 5w-30 heavy duty synthetic diesel oil"

https://www.amsoil.com/techservicesb...t%20Tappet.pdf

EDIT: Yes Nissan knows what works BEST for their engines but unfortunately due to emissions control standards they're forced to recommend an oil that is "good enough".
DOUBLE EDIT: They also engineered the engine to run on GF-3 oil, NOT GF-5 oil.

 

I pretty religiously change at 3500 miles, so conventional VR1 seems like it may be a good try for me. Current 5w30 Valvoline HM makes the motor run like a song with minimal valvetrain noise but horrendous consumption. Nissan DID design it for conventional, so I may give it a go. It's been getting pretty toasty, so 10w30 seems like my ticket with my driving habits on cold starts. Valvoline seems to say that that oil shouldn't be used long-term for catalytic converters, but if we're talking it shortens like to 100k miles psssh, who cares. My FI have 15k miles on them currently, I'll take a $600 charge every 100k miles for oil consumption and smooth operation.

 

Yeah that's pretty much the exact same conclusion I came to.

 

Thanks for the advice, my (relatively minor to be honest) consumption issues will hopefully be assuaged this weekend. I should have figured that an oil question would bring people out of the woodwork immediately, G35driver delivers yet again (fairly certain BITOG might be one of the only more contentious/**** forums out there).

 

I don't mind oil discussions at all, it's just an opportunity to present a lot of information that most folks are utterly clueless about. When our vehicles were made the GL-3 oil was what the engineers designed it to run on, not just a specific viscosity but a very specific TYPE of oil and additives. Now with pollution control mandates practically outlawing that specific type of oil we're forced to find something that will work good enough. Unfortunately pollution control mandates don't actually make machines run better, the government sets forth restrictions and it's up to the industry to figure out how to engineer something will hit the mark of an EVER SHRINKING TARGET.

They do their best but every step forward in emissions control is a step backwards for mechanical reliability and longevity.

-We suck dirty crankcase air back into the intake which lowers octane, fouls intake plenums, fouls throttle bodies, and fouls valves because we are required to by mandate.

-We suck up to 50% EXHAUST AIR back into the intake via EGR (thank god the G35 didn't have an EGR valve...) which severely fouls intake plenums and throttle bodies and destroys valves because we are required to by mandate.

-We lubricate with oil that has the best of it's lubrication safeguards removed because we are required to by mandate.

-We burn gasoline that's mixed with 10% ethanol, an inferior fuel (for our specific application), because we are required to by mandate.

-We are forced to reduce our NOX emissions via the use of restrictive exhaust catalyst instead of by simply increasing the mpg of the vehicle because we are required to by mandate (My friends Suzuki Alto in the Netherlands is currently pulling about 80mpg... that engine in the USA would get less than 50mpg with emissions control equipment on it), because we are required to by mandate.

-We are required to keep diesel emissions in check with the use of EGR (already discussed, catastrophic reduction of efficiency in a diesel) and the use of urea solution to selectively reduce catalyst, destroys efficiency to the tune of about -80% fuel economy... because we are required to by mandate.

I'm all for reducing emissions by increasing efficiency, but our EPA slashes our potential fuel economy at the cost of up to -40% overall engine fuel efficiency which is staggering. When you can take practically any engine on the market, delete the cats, delete the PCV and EGR, and retune the vehicle and gain between +20 to +40% increase in fuel efficiency then the system is completely broken.

 

I imagine it was considerably worse in the mid 1970's when they rushed that out.