I have just bought a 56 olds super 88 with a 324ci rocket engine. I have 2 questions. The first is: is it ok to use synthetic oil on such an old engine? The second is: What viscosity should i use? The car has been sitting for 6 years. It does kick over when i spray starting fluid into the carby, so its not siezed. The guy at the spare parts store thinks i should use a 10w 30, but i think this might be a little thin for such an old engine. Any advice would be greatly appreciated...thanks in advance!

 

Typically, unless you have a fresh rebuilt engine, syn oil is not a good thing to use. Oil will pour out of the motor in the smaller cracks in the gaskets that reg oil won't.

Weight? IDK. 10w 30 sounds good, but ask around

 

Ozzy, first off, Welcome to CO!

Secondly, Oil is always an arguement waiting to happen on an automotive forum.

Personally, I use conventional 10w 30 in my older engines, read that '84 and older, and havent' had any trouble to speak of.

This may well turn out to be an informational thread and I'm looking forward to it.

Jeff

 

I use 10W30 in my old cars, 66 is the oldest. I've had good luck. Just do regular oil changes. When I had a engine I was worried about I'd run straight 30 in the Summer, hot months.

I tend to stick to one brand oil and try not to change brands every oil change.

Don

 

It might surprise you that the factory recommended 20W oil in those engines. The only place I see that anymore is in an ag supply store.

If it were mine, I'd run straight 30 weight good quality diesel oil. Modern gas engine oil formulations don't have as much anti-scuff additive as they did, which is no big deal on a modern roller cam engine, but it's a really big deal on flat tappet engines such as our beloved old Rockets. Diesel formulae aren't as good as they were two years ago, but still better than gas oils which have none.

I would NOT use synthetic oil in that engine. I think it would be leaks waiting to happen. Synthetic is great for modern engines that see daily use, but I'm leery of using it in an older non-rebuilt engine that sees typical collector car duty.

 

My vote is for Straight 30 as well. I've been running it for years. It's warming up outside finally. Something about my orange juice in the morning being thicker than my oil bothers me.

 

This is an interesting question. I always use 10W30. I wonder if there is really any difference once the oil is brought up to operating temperature? Just imagine how hot it is in the crankcase, let alone the combustion chamber!

 

I have a 65 cutlass with a 350 in it and I use rotella 15w40 Its meant for diesels but it helps clean the gunk out! My engine had build up in it when I bought the car and I used the rotella and Its cleaning the gunk up! And they say that Rotella is the best of the diesel oils.

 

I've used synthetic oil in a 130K mile 1970 pontiac V8 without problems. Call it a myth or call me lucky. Your call.

 

I normally use 10w40 in the older cars. My cutlass gets either 20w50 or 15w40 deisel oil. No problems yet.