[1985, very stock]

Specified oil for the 1985 Corvette is 5W30 and would have been conventional ("dino"), not synthetic. In the mid-1980s, no brand was yet specified.

Under my ownership (from 47k to the current 69k) the car has received mostly dino with some Mobile 1 synthetic. The questions:

1) Should I be using dino, blended/hybrid, or synthetic?

2) Is there any advantage to using one of the high mileage oils as I close in on 70k?

3) Do folks have vendor preferences?

I don't think it's a huge deal either way. Personnaly, if it didn't leak with Mobil 1, I'd run it. That being said, I ran a SBC in my Chevy van to 200k on Quaker State dyno @ 175k it was using 1 qt. per 3,000 miles.

2) Is there any advantage to using one of the high mileage oils as I close in on 70k?

I don't like the stuff. I put it in my Silverado (5.3 Vortec) and it started to smoke on startup, changed back to M1 and it cleared up.
However, I've read where guys don't have a problem with it too.

The only problems with synthetics is how they clean and expose seals to leak that may not have leaked before. But since the inside of the engine is already clean, and has stayed that way, you are ok.

I would used the M1 5-30... or, because of the age, go with M1 10-30. Either will work ok.

Thanks, Bill and Andy.

I play it safe with my high mileage vehicles with a blend. No leaks.


Stir the pot.