thatonedude1

I recently saw 270 degF oil temp in my HPDE events. It led me to thing that at this temperature, we would be better protected with a 10W-40 to maintain some viscocity. GM says not to do this, just use 5W-30. Comments?

greendot

read this

http://www.bobistheoilguy.com/motor-oil-101/

travisnd

I've run 10w40 synthetic in every C5 I've tracked. IMO it's the ideal compromise, more protection than a 30 and less heat/friction than a 50.

Kubs

I stick with 30wt oil. The bearing clearance on these engines are made for lighter weight oil. A good synthetic oil will be perfectly fine in higher temps even in a 30wt.

VetteDrmr

I've run 10w-30 in my C5 ever since I bought her in '02. 240k+ miles later, 8 years autocross and assorted DEs and my Blackstone analyses are still fine.

One thing I did do was put on an external oil cooler; autox (esp. the slower 1st gear courses) just put too much heat into the oil.

That BITOG piece was an interesting read. Especially the part about the difference in viscosity at 150C (302F) between the 30 and 40 weight oils, difference was almost nil!

Have a good one,
Mike