I've spent a good deal of time trying to determine the ideal oil for my '86 IROC-Z. My last oil change I switched to Mobil 1 5W30 synthetic, but in looking back I think that 5W30 is too thin for a small block from the 80s. I want to step up a few thicknesses and possibly use Mobil Delvac. Delvac is a diesel engine oil but apparently works great in gasoline engines, too. It's mainly used by trucking companies as a fleet oil. It comes in two flavors: Delvac 1300 (mineral, 15W40) and Delvac 1 (synthetic, 5W40). Has anybody used these oils before?

I'm also thinking of standard Mobil 1 0W40; because it's a synthetic it's different than "regular" 0W40. I only drive this car in the summer and I drag race it weekly.

 

I've used Delvac 1 in gasoline engines. I get it in 1 gallon containers for about $16. I'm not positive about the formulation, but my belief is that it contains more detergents than the SG rated Mobil 1. Diesel engiens more an immense amount of air and produce considerably more carbon, so the oil tends to get more particulates and contaminants.

If there is some economic reason you prefer the Delvac 1 over Mobil 1, there is probably no reason you can't use it successfully.

 

Nope, no economic reason but I'd just like to run the best oil that I can (isn't that the goal of all of us, though? ). I'm glad to hear that you've run it successfully.

 

Cn't you just use dino oil but add half a quart of ATF? I have been doing that and i have been noticing a lot less smoke from my engine. I would get a piston ring expander/conditioner too if you are worried about miles.
--Dan

 

Just use Mobil 5w-30 or 10w-30 syn. oil and you won't have to worry about it any more. Stock type engines will go 200,000 plus miles. Change it every 5-10,000 miles.

 

use 15W50 in the summer for a performance small block and 5W30 in the winter unless you're car is parked outside, then use 0W40, don't use any 0 weight multigrades in the summer, the oil pressure will be way too low.

 

Yep, in every one of my motorcycle (and truck) engines. In particular in my wet clutch babies. Delvac has LESS friction modifiers in it that regular oil b/c it if formulated for fleet vehicles(so it does not have to conform to certain tests ). As for the detergents, IMNSHO I beleive they are about the same as the regular stuff.
I pay only $5 a gallon for the regular Delvac.