VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc synthetic oil

Some have said use of synthetic oil in older engines causes them to leak. Has anyone experienced this with 216 and 194 engines?
Thanks,
Sid

have tried synthetic oils in my "old" cars and had no change in leaks.
Actually there is no good reason to use synthetic in "old" cars for the most part.

The PO of my 48 was using synthetic in the 216 and the rear main seal was leaking badly - leaving 8 - 12 inch puddles of oil under the car when the engine was shut off. I switched over to Castrol High mileage 10W - 30, and, the leak is now much reduced - typically a 2 - 3 inch spot.

Regards:
Oldengineer
48 Fleetmaster Town Sedan

If its reduced, it may be a good time to check the dipstick.

Thanks though, I thought for the same weight oils, it would be the other way around, if any difference was noted at all.

Charlie

Charlie and others,
Synthetic motor oil will leak where mineral oil will not.

Thanks guys, I'll buy some Rotella soon.
Sid

What is special about Rotella? It is formulated for diesel engines and in its present form contains no more ZDDP than conventional gas engine oil.

a friend advised that rotella has more ZDDP than other oils. I have not personally done the research. What do you recommend?
Sid

The amount of ZDDP has been reduced in the later diesel oils for the same reason it was reduced in the gas engine oils.
There is enough ZDDP in conventional oils for any 6 cylinder Chevrolet engine unless the camshaft has been replaced with one of questionable quality.
Prior to the 1950's there was no ZDDP in the oil and a Chevrolet engine never wore the lobe off of the cam.

harlie:

I watch the dipstick like a hawk - especially with the rear main seal problem my car has. I also frequently check the gear lube in the tranny as well, because it too leaks a bit. When I bought the car, I found Pennzoil synthetic oil in the trunk, and the car was leaking big puddles like I mentioned. The first Summer I owned the car, I tried Castrol GTX in her, and, the leak seemed to slow some. Then, last Summer, I switched to Castrol High Mileage, and, the leak diminished further. The car's been on a number of trips this Summer, and, she's used about 1/4 of a quart.

Regards:
Oldengineer

Well, can't argue with that. Sounds good to me.
Charlie

Charlie:

When I bought the car I figured I've have to put a rear main seal in her. I've slowed the leak down to the point where I'm just going to put up with it for the time being.

Regards:
Oldengineer

First:
Good synthetics will not leak any more than a mineral oil of with the same additive package. When you switched to a high mileage oil, you were changing to an oil with a higher synthetic content - from group V synthetics that are higher in solvency, softening the seal that had hardened over the years. You can also soften them with AutoRx. Often people switch to a synthetic like Mobil 1 that does not have the seal conditioners in it since it is normally used in newer gasoline cars.
(I have synthetic in my 88 BMW and 60 Corvair, but it is CI-4 -- diesel formulation)

The AutoRx solution is a good one for leaking seals. The esters in it are similar to the ones we use in automatic transmission conditioners to clean up clutches and soften seals to stop leaks.

Second:
ZDDP - The diesel formulations were reduced, but to 1200 ppm of phosphorous. Gasoline oils to 800. So there is still a big difference and for you are better off running Rotella or other diesel formulations. I have several good options and the theories behind them in the following paper

If you want to know more, check out this report:
Selection of motor oil for flat tappet engines

I don't know about oils sold in South America but in the US the diesel oils are now rate SM same as gas engine. They have the reduced 800 PPM of ZDDP. This includes Rotella. This is due to the newer emission equipment on US diesels. They also must use low sulfur fuel.

Most oils these days are at least 40% synthetic due to the chemists additives that are put in, some brands admit the additives while others claim full synthetic.
Tony

Hi there Richard,
you have an amazing web site, I spent a long time reading all the links etc. The article on OILS is very comprehensive and easy to understand.
Thank you for posting the information, I think that you must at least be an engineer by profession and the time an effort that you have taken to create the website is appreciated.....

Peter

The CI-4 is the "older" diesel oil, but the newer spec CJ-4 is REQUIRED by most if not all current diesel engine mfg's and is also APPROVED for use in the older engines thus eliminating the need for someone with a mixed fleet to carry two different oils.