What weight engine oil for a 302?

Hi Guys,

Just wanted to get your opinions on what weight oil to use in a 302 with aluminum heads. I usually use 10w-30. I just won a case of Valvoline
5w-30 and am not sure that weight oil would be good for the engine. I'm in Florida where its getting really hot now too. I was also considering going synthetic. Heard some good things about that.

Comments are appreciated

 

Anyway you can trade it?
It might be ok, but I really like my Valvoline 10w-40

 

If the bottom end hasn't been rebuilt, synthetic would probably not be a good idea. It'll probably burn it and leak everywhere. I run 10w30 Castrol in the winter and 10w40 Castrol in the summer.

 

You didnt mention how many miles are on that motor. I think the 5w-30 is too thin for your Mav. With aluminum heads, I am assuming its been rebuilt. I'd use 10w-40 synthetic. I think Amsoil is the best but you will get different opinions on that. I think Mobil1, royal purple, and quakerstate are all highly rated synthetics as well. You just dont want to break in a new motor on synthetic. My rule of thumb is synthetic after 5000 miles.

 

I use Castrol 10-40.

 

+1

 

Castrol GTX 10-40 with about a half quart of molasses to quiet down those lifters.

 

You can use a synthetic regardless of mileage on engine.As for specific viscosity...5W 20/30 are formulated for todays engines which run much tighter bearing clearances.(cold 5 weight will get into the bearings easier than a 10W on the newer engines)Some new cars require a 0W20 oil.in your instance I would run a 10W30/40 unless you are runnning seriously tight bearing clearances.Synthetics have come a long way since their inception.The additive packages in em now dispell the old tales of leaking past seals or cooking off prematurely.Yes you can run em in older engines,actually if your engine is a smoker it will smoke a bit less with a synthetic in it.

 

As Mavman said - weight of oil depends on bearing clearances. I go by old school method - 10psi oil pressure per 1000 RPM. If you expect to max out at 5000 RPM I would want to see 50 psi but not less than 25 psi at idle. 10W30 works pretty well with normal 302 clearances which would be around .002".

Cleaver

 

I've experimented a lot with synthetic lubricants over the years in my vehicles. It really depends on the engine. I can run my 4 liter Jeep on synthetic 5 or 10w30 all year with increased fuel mileage(winter) and easier starting. It doesnt burn it any faster then conventional oils.
My 300m Special with a 3.5 HO doesnt do well with synthetic in the summer. It burns it up quicker than conventional oil. Much higher engine temps and a ton more RPM than the Jeep. I drive the 300 pretty hard and it shows in the oil consumption synthetic vs conventional. The 3.5 just seems to use synthetic more. Have customers with the same issue with this engine.
I use all synthetic fluids in my vehicles. Diffs,transfer case and trans. Huge difference in cold weather. 15% increase in fuel mileage in Winter in my Jeeps.
I run 10w30 conventional in the Mav.

 

By personal experience trying Mobil 1 in my 200, I would strongly disagree. It visibly started burning oil and it started leaking out the rear main seal and the oil pan gasket. The engine had 35,000 original miles on it at that point, with brand new valve seals and everything. I drained it and went back to Castrol when it burned and leaked enough out that the lifters got noisy. I expected as much, but thought it might be alright since it was such a low mileage engine. I thought wrong.

 

Low or high mileage doesnt matter as much as it still has 30 year old seals, and thats where the problems occur.

 

lol