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View Full Version : Anyone run Synthetic on a flathead



Etcetera
03-07-2005, 10:07 PM
I'm a big fan of synthetic in my 4 wheeled vehicles, but was wondering if synthetic would be appropriate in a 80" flathead? It's a fresh rebuild with a couple thousand miles on it.

Eric

rwpatton
03-07-2005, 10:15 PM
Etcetera If you run syn in a flatty it will more than likely leak like hell.

Engine case tolerances were no where near where they are on a modern engine. Your flat head IMHO prefers 60w.

Hope this helps.

RW

Wide
03-07-2005, 10:23 PM
Have to agree with RW, the manafacturing from back then was not up to snuff as far as metal, I seen folks put syn in old iron (pre 85 or so) & have it leak right thru the metal itself.

Stick with the dino :D

Etcetera
03-07-2005, 10:30 PM
I can get 60w syn, other than leaking, would it hurt anything to try it?

When it get's hot, into the 90's, should I stick with 60w, or go 70?

Eric

rwpatton
03-07-2005, 10:49 PM
Other then making a mess I do not believe it would cause damage to the engine.

Call me old school but I would stick to conventional oil in that engine. ;)

70wt's good for over 90 weather but not absolutely required.

RW

Etcetera
03-07-2005, 11:31 PM
Good ol' dino it is then.

Thanks

Eric