Marvel's I believe is 99% mineral spirits, and also contain naptha which is a solvent, That's why I wouldn't add diesel since mineral spirits is very close to diesel viscosity wise. I think you had the same idea.

 

Sorry to be out of touch my screen went out on my lap top and I can only get on when I can get to another. I have already checked the PVC and its working with very little smoke coming out of the valve cover. Someone asked what weight oil I was running, 10W 30 Gastrol Highmilage. I ususally run just regular Gastrol but tried the highmilage since it has some sinthetic in it. Its got to be the valve seals, I'm hopefully replacing those this weekend. Its so dang hot were I live its tough to get out in the garage.

 

if its got synthetic in it, its going to smoke. its an old car that wasnt designed for synthetic. it will also start leaking if it doesnt, and leak more if it does. 10w30 is also a bit thin. try running mobile super 10w-40 and see how that helps after you get the marvel cleaned out.

 

Synthetic will make an old engine smoke? It is a roller engine I am presuming.. I run Rotella in my 86. It is recommended to use oil with higher levels of zddp, and Rotella or even Supertech universal would be good instead of spending 5 dollars a quart on "classic car" oil.

 

1) What?
2) Huh? It could happen....maybe....under certain circumstances.
None of this is "matter-of fact". This is how urban legends are born too! Oh man, who's been feeding you this stuff?

 

The same people that tout back pressure. lol

 

never hear of synthetic making one somke. I run a full synthetic in my old truck and its got a 180,000 miles on it. Not doubting you by any means and I appreceate your help just never heard of it. The highmilage oil thats in there is a low blend of synthetic, it cant hurt. Besides none of its helping, Ive driven the car 500 miles or so with the marval oil and its still doing it. Whats throwing me for a loop is Tuesday I was messing with it and as the car was sitting idleing and the back bumper was fogging up again like it was coolant. The car is black so it shows up very good. Its done this once before then goes away. Like I said Im going to give the valve seals a chance and if that doesnt work Im pulling this crappy 305 like a bad tooth. This new school car if going to get a good ol' old school transplant with the roller motor GM should of put in.

 

Does any one have any idea what valve seals work best on these 305's? Thanks!

 

Felpro makes good unbrella type teflon seals.
The Fel-Pro positive ones come in 2 materials, one for intake which seals better since it's more critical, and one for exhaust which don't seal quite as well but stand the heat better. My recommendation..

 

its normal for steam to be emitted from the exhaust if its idling. water is a by product of combustion.

and what i speak of synthetic oils is from personal experience. i tried it once in my geo, and it smoked like hell. went back to regular oil, didnt smoke nearly as much. my 305 had a few small leaks. put mobile 1 in it, leaked like hell and had blue smoke on start up. switched back to standard, leaks subsided, smoke went away. same with my 4.3 blazer. my new truck would use a quart of oil every 1k miles using 5w30 castrol syn blend. put mobil super in, now it only burns a half quart in 5k miles. its simple if you understand oil. synthetic oils are a much smaller molecule than conventional oil, almost 1/4 the size. thats why new cars have such tight engine clearences. (i.e. toyota 2.4 requires 0-20, rod journal spec is .0005-.0010", gm 3.8 requires 10-30, .002-.004"). if the tolerances were designed for the older product and have quite a bit of wear, the tolerances will be even looser, thus resulting in more oil consumption and/or leakage