Oil for 1990 GM 3.1L

[artificialist]

I doubt the engine needs extra ZDDP, that typically is a problem on high performance cams. If your engine is a stock rebuild, the cam you have isn't aggressive enough to need extra ZDDP.

I would just buy whatever reputable 5w30 is on sale and use that.

 

[addyguy]

I love those old Z-24's, they were a great-looking, quick little car for their day.

Any HM 5W-30 would be a great oil for it.

 

[B20z]

Looks clean. You don't see any of those around here anymore.

10w-30 Defy would probably be my pick. Much harder to go wrong here than to do fine. Enjoy.

 

[Mauro]

Originally Posted By: SilverC6
I'd stay with your regular PYB and AC/Delco or Wix.

I have a Chevy Lumina with the 3.1 and that combination has worked fine through 127,000 miles.

I'd recommend you change the coolant ASAP.

Flush and get the Dex-cool out of the engine.

I lost a intake manifold gasket at 107,000 miles.


The manifold gaskets on that engine were [censored]. Can't blame dex-cool for that. I had an 97 Grand AM GT 3.1 and I replaced the gaskets twice on my car. The second time I used a Felpro gasket (Aluminum with coated rubber) and never had an issue again. I ran whatever 5W30 that was on sale and it ran great up until I sold it with over 144K miles.