I have a 1991 429 and was wondering what kind of oil I need to run in it. Do I need to run a 10-30 or 10-40? Or I keep Rotella 15-40 around anyway for equipment, would I be better off to use that? Thanks for any help you can provide.

 

The 15-40 would probably be fine.

Any indication of what was previously run?

 

I'd go with the 15-40 also.It seems like a good all-around motor oil.I've used it for years in everything from pick-ups to construction equipment.

 

No clue about what was in it, I probally go with the Rotell a then. Thanks.

 

I used 15-40 in our old 429 powered truck.. And use it in all our current trucks. Ive heard its high in detergents, and thats why its not recommended in gas engines?? But I have no idea on that, just the word on the streets around here..