[Sakudog]

Originally Posted by travislambert

I have a similar question in the Ask Al queue:

http://www.camaro6.com/forums/showthread.php?t=516314

My guess is that it's more about how GM expects the cars to be driven rather than the car itself. I understand the comment about the aero, suspension, etc. playing a role in keeping the ZL1 1LE in the throttle a little longer, but I can't imagine that difference being significant. If that were the case, GM would probably need to have different oil recommendations for each road course too because the difference between track layouts would be far more significant in terms of braking vs acceleration time.

Agree with you 100% here... but, the Track Preparation guide has the same oil recommendations for the ZL1 car.

https://my.chevrolet.com/content/dam...tion-guide.pdf

[waterman]

[kaamacat]

Originally Posted by Sakudog

Agree with you 100% here... but, the Track Preparation guide has the same oil recommendations for the ZL1 car.

https://my.chevrolet.com/content/dam...tion-guide.pdf

The slight difference is...they are saying 15w50 -only- for ZL1 1LE, and most likely they are assuming the 1LE variant will be a road course use car running harder/longer. (I'd rather they come back with a year-round 5w40 or 0w40 like i had in the ViperGT or GT3RS. Never a issue with cooling, oil temps nor failure). In-fact just swapped back to 5w30 yesterday until the next track event. (Pennzoil UltraPlatinum, good stuff)

[baron95]

Originally Posted by travislambert

I understand the comment about the aero, suspension, etc. playing a role in keeping the ZL1 1LE in the throttle a little longer, but I can't imagine that difference being significant. If that were the case, GM would probably need to have different oil recommendations for each road course too because the difference between track layouts would be far more significant in terms of braking vs acceleration time.

That is not how GM does oil specs. The specs are done to cover "likely to be encountered worst case scenarios". So the track oil recommendation is probably determined by a driver pushing a car on a challenging track at something like 85F.

What it means is that if you are not pushing as hard or running on a cooler day or a less demanding track you will have more headroom (i.e. will be taxing the oil and cooling packages less).

I've tracked a C7 Z51 with 5W30 oil for 3 years, and that car would go to 300F oil temperatures in the blink of an eye, and had to be temperature managed (shifting ~1,000RPM below redline) to prevent hitting the engine protection ("limp") limits.

I'm doing 5W40 in the SS 1lE, because I want to be able to push more (closer to redline) and want a little bit more headroom, and even less warranty questioning possibilities.

My guess is the GM still needs to complete "likely worst case scenarios" this summer on the ZR1/ZL1-1LE before adjusting recommended track oil down to 0W40.

[travislambert]

Originally Posted by baron95

That is not how GM does oil specs. The specs are done to cover "likely to be encountered worst case scenarios". So the track oil recommendation is probably determined by a driver pushing a car on a challenging track at something like 85F.

What it means is that if you are not pushing as hard or running on a cooler day or a less demanding track you will have more headroom (i.e. will be taxing the oil and cooling packages less).

I've tracked a C7 Z51 with 5W30 oil for 3 years, and that car would go to 300F oil temperatures in the blink of an eye, and had to be temperature managed (shifting ~1,000RPM below redline) to prevent hitting the engine protection ("limp") limits.

I'm doing 5W40 in the SS 1lE, because I want to be able to push more (closer to redline) and want a little bit more headroom, and even less warranty questioning possibilities.

Perhaps I oversimplified my post. I didn't mean to imply engineers didn't take an engineering approach.

I don't disagree with what you've stated here, and "Likely worst case scenarios" seems like a good way to put it. I'm just skeptical about the theory of the ZL1 and ZL1/1LE having different oil specs due to the 1LE being slightly more track capable. Mechanically, the worst case scenarios for both cars should still be very similar. The most significant difference is much more likely to be the owners and where/how hard they drive.

I've also considered that maybe there is difference in the emissions systems which would make the reason for different oil recommendation obvious, but I'm not aware of any such difference.

I think this question is a great question for Ask Al, but this process is moving so slowly I'm starting to lose interest. The Corvette forum's Ask Tadge seems to move at a much better pace.

Originally Posted by baron95

...
My guess is the GM still needs to complete "likely worst case scenarios" this summer on the ZR1/ZL1-1LE before adjusting recommended track oil down to 0W40.

I too suspect we'll see this change in their recommendation.