Go from 5w30 to 0w40 in Corvette Z06?

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51
Location
Central Texas
I know this has been discussed before but I'm still uncertain on whether or I should change from 5w30 to M1 0w40 FS on my LS7 Corvette? GM seems pretty adamant in all of their literature to only use 5w30 DEXOS1, but I did notice in the '16 Cadillac CTS owner's manual that they say you can run a 0w40 DEXOS2 approved oil in the LT4 V8 for the track. I live in Central Texas so the winter's are usually mild and temps rarely go below freezing, (and I wouldn't drive the car then, anyways.) Wear Protection figures that I can find show an excellent 127,000 PSI for the 0w40 Mobil 1 FS Euro Car Formula and just under 118,000 for the M1 5w30 Advanced Full Synthetic. I know that I might see a slight drop in mileage but other than that, do I take any chances on anything in running 0w40 - will it wear out the emissions equipment or anything like that? The numbers below are from Mobil1's website (03/2017)
 
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17,284
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Upper Midwest
Originally Posted By: AirBull
I know this has been discussed before but I'm still uncertain on whether or I should change from 5w30 to M1 0w40 FS on my LS7 Corvette? GM seems pretty adamant in all of their literature to only use 5w30 DEXOS1, but I did notice in the '16 Cadillac CTS owner's manual that they say you can run a 0w40 DEXOS2 approved oil in the LT4 V8 for the track. I live in Central Texas so the winter's are usually mild and temps rarely go below freezing, (and I wouldn't drive the car then, anyways.) Wear Protection figures that I can find show an excellent 127,000 PSI for the 0w40 Mobil 1 FS Euro Car Formula and just under 118,000 for the M1 5w30 Advanced Full Synthetic. I know that I might see a slight drop in mileage but other than that, do I take any chances on anything in running 0w40 - will it wear out the emissions equipment or anything like that?
Well first off, Mobil 1 FS 0W-40 is not dexos2. So if that is a requirement you wish to accommodate then that's not the correct oil. And second, since you seem inclined to reference "wear protection" and PSI ratings, as I asked in your other question what does Chevrolet publish as a minimum PSI rating for your LS7 Corvette? How do you know that 127,000 PSI for the 0w40 Mobil 1 FS Euro Car Formula is "excellent" and just under 118,000 for the M1 5w30 Advanced Full Synthetic is not excellent?
 
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8,051
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Michigan
If you're only running your Z06 on the street, there is no need to switch to M1 0w40. But it wouldn't hurt anything if you did. The current formulation of M1 0w40 has a viscosity that is right at the bottom of the 40 range, so you may not even notice a drop in fuel economy. On late-model C7 Corvettes, the owners manual goes as far to recommend M1 15w50 for track use.
 
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South OZ
M1 0W40 is a lighter 40. There will be barely any difference between those two oils. The 0w40 is a better oil in my opinion.
 
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28,123
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Regina, Saskatchewan, Canada
Originally Posted By: AirgunSavant
Castrol Edge 0w40 is dexos2 compliant.
Not the Castrol Edge you'll find on any regular retail shelves in North America.... There are two different 0w-40 products, one of which, the A3/B4 we find in North America, and the other the 0w-40 dexos2, which you won't. I think the dexos2 0w-40 has a wear rating of 545,384,234.3706238 PSI. That's why we can't get it in North America.
 
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'Stralia
Originally Posted By: AirBull
Wear Protection figures that I can find show an excellent 127,000 PSI for the 0w40 Mobil 1 FS Euro Car Formula and just under 118,000 for the M1 5w30 Advanced Full Synthetic.
You should have read his blog a bit further....
Originally Posted By: Rat
8. 0W40 vs 5W30 vs 0W30 On the Corvette C6, Z06 Forum, perhaps the most popular oil the U.S. guys like to use is what they call, the 0W40 Euro blend Mobil 1. This oil is what GM calls for in the Owner’s Manual and also on the oil filler cap on C6 Z06’s sold in Canada and Europe, whereas 5W30 Mobil 1 is called for in the U.S. The rationale the U.S. Corvette owners typically use for choosing this 0W40 Euro blend Mobil 1 instead of following GM’s recommendation, is the thinking that this oil may have more zinc than U.S. oil, and their mistaken belief that more zinc and a higher viscosity can provide better wear protection, as well as their mistaken belief that 5W30 Mobil 1 is not very good. Also, on “Bob is the Oil Guy” Forum, 0W30 Castrol Edge with Syntec (black bottle), API SL, European Formula, made in Germany and sold in the U.S., is very popular. This is apparently because they favor the better cold flowing 0W cold viscosity rating (which is a good idea), and because of the thinking that this oil may have more zinc than U.S. oil, and their mistaken belief that more zinc can provide better wear protection. The Z06 guys as well as the Bob Forum guys, obviously feel this way based on emotion and guessing/speculation, because they clearly never had any test data to evaluate………………until now. All this calls for performing Engineering Wear Protection testing those 0W40 and 5W30 Corvette Z06 oils, as well as testing 0W30 oils, to see how they all compare. Then Z06 owners and the Bob Forum guys can take a look at actual hard test data numbers that will show the facts. With that information in hand, they can make an informed decision when it comes to selecting an oil that will truly provide them with the best wear protection. So, I tested the following motor oils: 0W40 and 5W30 Pennzoil Ultra 0W40, 5W30 and 0W30 Mobil 1 0W40, 5W30 and 0W30 Castrol Edge with Syntec (in the black bottle) NOTE: Castrol’s top of the line 100% Edge motor oil, comes in the gold bottle. . .more Rat mumbo jumbo . As you can see from these actual Engineering test values, all the 5W30 oils provide better wear protection than any of the 0W oils. But even so, any of these oils would be acceptable for normal daily driver use. However, for highly loaded High Performance applications where the best possible wear protection is desired, the obvious choice would be 5W30 Pennzoil Ultra, API SM or 5W30 Mobil 1, API SN, which are the only oils in this test that provide INCREDIBLE wear protection. So, GM got it right about which oil to recommend in their U.S. Z06 Corvette’s. One can only speculate that perhaps they expect the U.S. cars to be run harder, so they call for the best protection in those engines. Although, general availability in Canada and Europe may also play a part in what oil they recommend. Whatever the case, both oil viscosities had to meet GM’s endurance testing requirements. Folks can of course decide for themselves which oil they want to run in their own cars. But now, they have the accurate test data to make an informed decision. NOTE: After this piece was originally written, 5W30 Pennzoil Ultra, API “SM” has been phased out and replaced TWICE by a newer API “SN” version. See the Wear Protection Ranking List in Section 1, for the current psi value and ranking position.
Use whichever takes your fancy.
 
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4,398
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Connecticut
Running M1 0w-40 old version (vis 13.8) in my 1999 LS1 Camaro....it too specs 5w-30. Don't see any changes other than 2-3 psi higher on idle oil pressure. This oil is a popular choice among LSX enthusiasts, even for regular street use. I ran the M1 5w-30 for 4 years before this. I wanted the additional HTHS protection even for moderate street use. The M1 0w-40 shears down pretty fast. By the end of your 8K-10K OCI it could be down to 11.1-11.8, basically a 30 grade. I think 30 grades go up to 12.5 cSt at 100 deg C. In the higher temps of a Texas summer, I think the 40 grade will actually be better for your car. The guy with the LS7 in North Dakota is probably fine with the 5w-30 in summer.
 
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4,398
Location
Connecticut
As you can see from these actual Engineering test values, all the 5W30 oils provide better wear protection than any of the 0W oils. But even so, any of these oils would be acceptable for normal daily driver use. However, for highly loaded High Performance applications where the best possible wear protection is desired, the obvious choice would be 5W30 Pennzoil Ultra, API SM or 5W30 Mobil 1, API SN, which are the only oils in this test that provide INCREDIBLE wear protection. NOTE: After this piece was originally written, 5W30 Pennzoil Ultra, API “SM” has been phased out and replaced TWICE by a newer API “SN” version. See the Wear Protection Ranking List in Section 1, for the current psi value and ranking position. Oops. Don't look now, but 540RAT just contradicted themselves and undermined their own "testing" program. So the 30 oils are the best for the Corvette Z06 based on RAT testing up to 2013-2014? Those are the original RAT testing findings. And up to that point there weren't any 0w oils or any 40 grades leading the list. But now there are. M1 0w-40 FS, QSUD 0/5w-20. Those oils out rank the M1 5w-30. So I guess they should now be used in the Z06. It appears the Bitogers knew what they were talking about all along...and RAT didn't. RAT should take the time to update their own blog with these new findings. And should also take the time to figure out why the M1 0w-40 went from the bottom half of the list to his #1 rated oil of all time. Doesn't it even bother him a bit that 0w oils now head the list when they didn't before? Lots of discrepancies now that need explaining. At least we know the best oil to use for the Z06. Thanks Shannow for that little gem.
 
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28,123
Location
Regina, Saskatchewan, Canada
Originally Posted By: 69GTX
Lots of discrepancies now that need explaining.
That's what happens when you simply update "data points" without touching your conclusions at all, particularly when your data goes against your conclusions. This is another example of this blog's science at its finest.
 
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15,879
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NE,Ohio
So wait. We dont need millions and in engine testing now.. we can just call up this rat guy to get what oil is the best?
 
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17,284
Location
Upper Midwest
Originally Posted By: Rand
So wait. We dont need millions and in engine testing now.. we can just call up this rat guy to get what oil is the best?
You don't even need to call him, just go to his website. I'm emailing Ford, GM, Toyota, Honda and Mercedes Benz right now. Does anyone have a contact at ACEA?
 

AirBull

Thread starter
Messages
51
Location
Central Texas
Part of the problem is these oils have been changing over the past 2,3, or 4 years that unless it was tested recently, we can't be certain as to what it still is! So what are the advantages of 0w40 again? Better protection of the engine? Disadvantages would be? Reduction in mileage? Wear out the cats/emissions faster?
 
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17,284
Location
Upper Midwest
Originally Posted By: AirBull
Part of the problem is these oils have been changing over the past 2,3, or 4 years that unless it was tested recently, we can't be certain as to what it still is! So what are the advantages of 0w40 again? Better protection of the engine? Disadvantages would be? Reduction in mileage? Wear out the cats/emissions faster?
Who is testing what? I'm quite certain they meet the manufacturer's published specifications. Are you trying to claim they do not? If it were me I'd pay less attention to some goofy website and more to what is required by the manufacturer - and which oils meet those requirements.
 
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Messages
4,398
Location
Connecticut
Originally Posted By: AirBull
Part of the problem is these oils have been changing over the past 2,3, or 4 years that unless it was tested recently, we can't be certain as to what it still is! So what are the advantages of 0w40 again? Better protection of the engine? Disadvantages would be? Reduction in mileage? Wear out the cats/emissions faster?
The M1 0w-40 FS was tested recently by RAT. Most of the other Mobil / PP / Castrol oils have not been. Then again, this test has almost nothing to do with your car engine. The mfg's test the oils on every reformulation. You can be assured that all are recently tested. Better protection of the engine at high temperatures. Better oil flow at very low ambient temps vs. 5w. The mileage reduction would be fairly minor from vs. a decent 30 grade. Wouldn't wear out cats hardly any faster unless you have oil blow by. The difference in phos/zinc from M1 30 to 40 grade is at most 10-20%. So if you CATs were originally going to last 10 years on M1 5w-30 due to fouling...they might only last 8-9 yrs. If you do have considerable oil usage, then maybe M1 5w-30 or even a lower SAPs 5w-30 might be for you.
 
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