Rotella T4 15w40 + Lucas in a 93 Corvette Autocross Race Car

[OVERKILL]

If choosing between Mobil 1 5w30 and Mobile 1 10w40 HM, or Amsoil Signature Series 5w30 and 10w40? (actual oils 80s/90s Corvette owners choose between)

10w40 every time

The point is, you can't just go by the grade. You are claiming 10W-40 is the better option, but the reality is that many of the 10W-40's are cheaply blended oils with no higher concentration of AW additives than their 5W-30 siblings, despite being permitted to have them under the API regs.

The Euro 5W-30 I shared above is a prime example of a 5W-30 that's better than the 10W-40's listed, because it has to pass some demanding, and current, OE approvals (BMW's in this case), while the 10W-40's don't, because nobody calls for that grade. This is the approval table from Mobil, note there isn't a single X in the 10W-40 column beyond the standard API one:

Interestingly, the 5W-30 has a superior flashpoint to the 10W-40 too:

The 10W-40 also has API constrained levels of phosphorous, despite not requiring it, which, as you'll note, is considerably lower than the BMW 5W-30:

If you are hell-bent on using an xW-40, I'd be far more inclined to use a full-SAPS Euro 5W-40 or 0W-40, which will be a more capable lubricant.

 

[kschachn]

The point is, you can't just go by the grade. You are claiming 10W-40 is the better option, but the reality is that many of the 10W-40's are cheaply blended oils with no higher concentration of AW additives than their 5W-30 siblings, despite being permitted to have them under the API regs.

The Euro 5W-30 I shared above is a prime example of a 5W-30 that's better than the 10W-40's listed, because it has to pass some demanding, and current, OE approvals (BMW's in this case), while the 10W-40's don't, because nobody calls for that grade. This is the approval table from Mobil, note there isn't a single X in the 10W-40 column beyond the standard API one:
View attachment 176213

Interestingly, the 5W-30 has a superior flashpoint to the 10W-40 too:
View attachment 176214

The 10W-40 also has API constrained levels of phosphorous, despite not requiring it, which, as you'll note, is considerably lower than the BMW 5W-30:
View attachment 176217

If you are hell-bent on using an xW-40, I'd be far more inclined to use a full-SAPS Euro 5W-40 or 0W-40, which will be a more capable lubricant.

Good post and accurate.

 

[userfriendly]

Given the 10W40 options from Mobil, I’d go with the motorcycle one.
API, ACEA and other governing bodies limit evaporation rates (noack). They also have stay in grade guidelines.
So picking an engine oil that carries manufacturer’s’ approvals and licenses eliminates the risk of buying a cheaply blended product.

 

[Robvette]

Xw40 or Xw50.

I personally prefer 18cSt. The reason for no elevated wear metals in my last UOA with high Si? Possibly 20 micron filtration coupled with 18cSt "abrasive particles equal to or larger than the oil film thickness will cause wear". I'm sure that can't be true.

It really doesn't matter what I type.

I originally shared 5w30 was specified for 80s/90s Corvettes due to CAFE.
BITOG members tore me a new one.
I confirmed this to be true by corresponding directly with the leader of the Corvette Development Team during that time.
Doesn't matter.
BITOG members just change the argument to "some modern 5w30 that I come up with is still better".

 

[ZeeOSix]

The Corvette Development Team Leader specifically said 5w30 weight was recommended because of CAFE. And that he did not use 5w30 in his personal Corvettes.

That was "thick vs thin" of the 80s and 90s.

 

[Brian123]

Xw40 or Xw50.

I personally prefer 18cSt. The reason for no elevated wear metals in my last UOA with high Si? Possibly 20 micron filtration coupled with 18cSt "abrasive particles equal to or larger than the oil film thickness will cause wear". I'm sure that can't be true.

It really doesn't matter what I type.

I originally shared 5w30 was specified for 80s/90s Corvettes due to CAFE.
BITOG members tore me a new one.
I confirmed this to be true by corresponding directly with the leader of the Corvette Development Team during that time.
Doesn't matter.
BITOG members just change the argument to "some modern 5w30 that I come up with is still better".

I think you are talking about the other Thread you started?

 

[Thermo1223]

Xw40 or Xw50.

I personally prefer 18cSt. The reason for no elevated wear metals in my last UOA with high Si? Possibly 20 micron filtration coupled with 18cSt "abrasive particles equal to or larger than the oil film thickness will cause wear". I'm sure that can't be true.

You mean the junk Lucas UOA? Hardly definitive...

Modern oil is better it's like comparing an LT1 to an LS6, hardly fair and seriously lacking in objectivity.

 

[ZeeOSix]

If you are hell-bent on using an xW-40, I'd be far more inclined to use a full-SAPS Euro 5W-40 or 0W-40, which will be a more capable lubricant.

Which Mobil 0W-40 formula is used in the C8 Corvette? ... think it's the ESP. I'd think if it's good enough for a C8 Vette, it would be good enough for any older Vette.

 

[userfriendly]

Xw40 or Xw50.

I personally prefer 18cSt. The reason for no elevated wear metals in my last UOA with high Si? Possibly 20 micron filtration coupled with 18cSt "abrasive particles equal to or larger than the oil film thickness will cause wear". I'm sure that can't be true.

It really doesn't matter what I type.

I originally shared 5w30 was specified for 80s/90s Corvettes due to CAFE.
BITOG members tore me a new one.
I confirmed this to be true by corresponding directly with the leader of the Corvette Development Team during that time.
Doesn't matter.
BITOG members just change the argument to "some modern 5w30 that I come up with is still better".

Some bitog members won’t give you the validation that you are looking for and default to xw30.

 

[cheesepuffs2]

You have no data to support recommending 5w30 over 10w40 for 80s/90s Corvettes in any driving conditions. Because ... wait for it ...
...
...
... that data does not exist.

Nor does data to prove that a 40 or 50 weight oil will protect your engine better than a modern formulation 30 weight. What you shared, while it's a cool anecdote, is just that. You're basically telling people, "what you say is just an opinion and not a data point", while passing along a story from somebody, where while that person is notable, they are still not a tribologist themselves, and you're pitting their rule of thumb against somebody else's rule of thumb but touting one as more factual than the other.

At the end of the day, who cares. It's your car, run what makes you feel good. You don't need to justify to anybody why you're running what you're running. Run what you run and have a good time out there. That's what it's about and it's why you bought this car in the first place. Not to spar with people online about viscosity.

 

[cheesepuffs2]

Xw40 or Xw50.

I personally prefer 18cSt. The reason for no elevated wear metals in my last UOA with high Si? Possibly 20 micron filtration coupled with 18cSt "abrasive particles equal to or larger than the oil film thickness will cause wear". I'm sure that can't be true.

Reading this, I feel like you're way over-thinking all of this when you don't have to. It's a stock LT1. Run whatever and rest easy.

 

[skippermatt]

I’d pick viscosity based off bearing clearance, which are what .0025” stock? Oil temperature which should ideally be around 220 degrees, and load on bearings, which probably wouldn’t be all that much cause it’s not a nitrous engine and not being used towing at low rpm/high load lugging up a hill. With all that being said, I’d probably use some sort of xxw40 which would probably be overkill. Most racers tend to prefer thinner oils because they lead to cooler bearing temps/more power, but thick enough to protect. But at the same time I used redline 5w30 in a built sbc and the results were great. But with all that said a sbc/lt1 will not care what oil is in it and will run happily on anything.

 

[Brian123]

Reading this, I feel like you're way over-thinking all of this when you don't have to. It's a stock LT1. Run whatever and rest easy.

Actually, I think the OP started a Thread and expected everyone 2 agree with what he said.

 

[Robvette]

Which Mobil 0W-40 formula is used in the C8 Corvette? ... think it's the ESP. I'd think if it's good enough for a C8 Vette, it would be good enough for any older Vette.

Supercar 0w40 and Supercar 5w50. Mobil says on their Supercar oil website that "For those with a Corvette model produced before 1993, we recommend Mobil 1 15W-50 for both street and track use."

Reading this, I feel like you're way over-thinking all of this when you don't have to. It's a stock LT1. Run whatever and rest easy.

fwiw - I'm not asking for advice on what to run But, if you want to know what oil Mobil specifically recommends for early Corvettes, click the link below and then "What if I own a previous generation Corvette?"

Mobil 1™ – Corvette’s recommended motor oil

Mobil 1 Supercar is the first motor oil designed specifically for Corvette to deliver maximum performance on the street, on the track, and back, with one motor oil.

www.mobil.com

Actually, I think the OP started a Thread and expected everyone 2 agree with what he said.

I shared info, folks disputed it. I shared proof, folks changed the subject to continue to argue. It's silly, I know. This link from the Mobil 1 Supercar website won't help either - just watch.

That was "thick vs thin" of the 80s and 90s.

Imagine if Lingenfelter, Callaway, the Corvette Design Team Leader and Mobil 1 all recommended the same thing?

Mobil 1™ – Corvette’s recommended motor oil

Mobil 1 Supercar is the first motor oil designed specifically for Corvette to deliver maximum performance on the street, on the track, and back, with one motor oil.

www.mobil.com

 

[ZeeOSix]

I’d pick viscosity based off bearing clearance, which are what .0025” stock? Oil temperature which should ideally be around 220 degrees, and load on bearings, which probably wouldn’t be all that much cause it’s not a nitrous engine and not being used towing at low rpm/high load lugging up a hill. With all that being said, I’d probably use some sort of xxw40 which would probably be overkill. Most racers tend to prefer thinner oils because they lead to cooler bearing temps/more power, but thick enough to protect. But at the same time I used redline 5w30 in a built sbc and the results were great. But with all that said a sbc/lt1 will not care what oil is in it and will run happily on anything.

If that Corvette was only being used for Auto-X and spirited street driving, then a good 5W-30 would work well. If it's ever used on a track with extended runs, then I'd go with a good xW-40, like the Mobil 1 oW-40 used in the C8 Corvette ... or just go with the 0W-40 to cover all your bases. Since it's a 1993, then per Mobil they wouldn't recommend the 15W-50 per the info in the post above this one by Robvette.

 

[AmBeRnEcTaR]

Supercar 0w40 and Supercar 5w50. Mobil says on their Supercar oil website that "For those with a Corvette model produced before 1993, we recommend Mobil 1 15W-50 for both street and track use."

fwiw - I'm not asking for advice on what to run But, if you want to know what oil Mobil specifically recommends for early Corvettes, click the link below and then "What if I own a previous generation Corvette?"

Mobil 1™ – Corvette’s recommended motor oil

Mobil 1 Supercar is the first motor oil designed specifically for Corvette to deliver maximum performance on the street, on the track, and back, with one motor oil.

www.mobil.com

I shared info, folks disputed it. I shared proof, folks changed the subject to continue to argue. It's silly, I know. This link from the Mobil 1 Supercar website won't help either - just watch.

Imagine if Lingenfelter, Callaway, the Corvette Design Team Leader and Mobil 1 all recommended the same thing?

Mobil 1™ – Corvette’s recommended motor oil

Mobil 1 Supercar is the first motor oil designed specifically for Corvette to deliver maximum performance on the street, on the track, and back, with one motor oil.

www.mobil.com

View attachment 176375

I think what most of the guys are saying is, a 5W-50 or 15W-50 will lubricate just fine.
The fact that your particular car is gonna get run up to redline and back in first and second gear for brief periods repeatedly whilst constantly stabbing at the brakes and cornering isn't really creating the internal engine torture that you think it is.

It's not a high spinning, high compression engine. It's a cool car no question however a modern day 5W-30 FS will slosh around and get to all those moving parts just fine in the environment you're exposing it to.

Thinner oil will disperse heat better, while allowing the engine to spin more freely. If you're looking to create more unnecessary oil pressure then fill your boots.

Love the car

 

[Robvette]

... a modern day 5W-30 FS will slosh around and get to all those moving parts just fine in the environment you're exposing it to.

Thinner oil will disperse heat better, while allowing the engine to spin more freely. If you're looking to create more unnecessary oil pressure then fill your boots.

what's interesting to me is that sooooo many folks here are recommending 5w30 over a heavier oil for this application.

• the Corvette Development Team Leader said heavier is better, 30 weight is for fuel economy optimization
• Lingenfelter used heavier (10w40)
• Callaway used heavier (15w50)
• and Mobil 1 currently recommends 15w50 for pre-1993 Corvettes

there's no cost difference between M1 5w30 and M1 15w50.

i just don't get why so many people are super pushing 5w30. yes, 5w30 is probably adequate for most drivers - but if both oils are sitting on a shelf next to one another, then 15w50 seems like the easy choice. or at least a 40 weight oil.

Mobil 1™ 15W-50 | Mobil™ Motor Oils

Mobil 1™ 15W-50 is designed to help keep your engine running like new by providing outstanding wear protection, cleaning power and overall performance.

www.mobil.com

 

[ZeeOSix]

and Mobil 1 currently recommends 15w50 for pre-1993 Corvettes

I'd just go for this per Mobil's recommendation for a 1993 Vette as you already eluded to. This stuff will take whatever beatings you plan for this car. You're going in circles down a spiral rabbit hole.

 

[mahanddeem]

"..Says loads of racers use this same oil combination with great results.."

To give credit when due, they did not specify which results they were after, maybe less bloat and farting at night was their great result.

 

[TiGeo]

Wait....how about