Mobil 1 and Fuel Stabilizer

[Duke W.]

Re: Mobil 1 and Fuel Stabilizer

ZDDP level may be OK, but 15w50 is mighty high viscosity. Rotella T is available in 10W30 and would seem ore desirable and outweigh any perceived advantages of synthetic. Duke, what say you?

Most CJ-4 brands are available in 10W-30 grade, but 15W-40 is more commonly stocked by retailers.

I don't see any issues with 15W-50 for typical vintage Corvette use, which is normally in mild to warm weather. Back before P was reduced in S-category oil I ran 20W-50 in all my cars. The lowest cold start temperature in my coastal California climate was rarely less than 40F, so 20W was okay and the 50 SAE viscosity at 212F means higher film strength than 30, which can help in boundary lubrication situations. It may cost a tenth or two of a MPG, but I was willing to sacrifice insignificantly higher fuel consumption for more lubrication margin.

If you look at a seventies vintage GM owners manual you will see that 20W-50 is acceptable for the ambient temperature range of 20-100+F, and since there is no fundamental difference between sixties and seventies engines that would effect the recommended oil viscosity, it's reasonable to assume that GM would have been okay with 20W-50 in those conditions for sixties vintage engines, but you won't find it listed in sixties vintage owners manuals, because the 20W-50 viscosity grade did not become commonly available until the early to mid seventies.

Duke

[Frank D.]

Re: Mobil 1 and Fuel Stabilizer

Edmund,
One more thought on the Mobil 1. I was told a long time ago and have experienced it my self with leaks. You may have minor leaks or seepage which is normal for an old Corvette. They will get worse with the Mobil 1. That stuff will seep out anywhere it can! Love the stuff other wise and run it in all my newer vehicles! I personally run the Walmart brand CJ-4 oil in my vintage stuff. Have had zero problems in 7 years.

I don't know what to say to that.... Yes, if your car leaks; it'll still leak with synthetic. Synthetic doesn't stop leaks, and, it doesn't cause them....regardless of the myths.

As Duke so eloquently stated the 15W-50W weight is fine for our cars. That specific Mobil 1 product and viscosity is targeted right at vintage engines.
And yes, its not cheap....

[John S.]

Re: Mobil 1 and Fuel Stabilizer

Frank,
Have you read up on what the difference is between "regular" oil and synthetic. The way it was described to me in lay mans terms was that when they synthesis the oil stock to synthetic that it allows it to fit in smaller places. I do not have a chemistry degree, maybe someone here that has one will chime in. All I can say is try it. Post your results!

[Frank D.]

Re: Mobil 1 and Fuel Stabilizer

Well, in fact, I've already tried it.
I have had Mobil 1 in my '61 for 8 years and in my '63 for 2 years.
The '61 had the same leaks it had when I bought it (rear main oil seal seeping), and, the '63 has NO leaks at all (I know - hard to believe!)...I replaced the rear seal in the '63 shortly after purchasing it though.