The Stovebolt Site Forums The Shop Area Engine Shop Correct oil

This is almost too embarrassing, but I have to ask. I am working on a friends recently somewhat restored 1st Gen '55 3100 1/2 ton. It has the small six which has been rebuilt and is running an external oil filter. What would be the proper oil to run in this engine? It has about 100 miles on it since it was finsihed.

The factory recommendation would have been MS30 in the summer and MS20 in the winter and even MS10 in sub zero. MS with the highest grade of oil made for gasoline engines of the day. ML was light duty, non detergent, MM moderate duty and MS severe duty. Those ratings are meaningless today. My father began selling lubricating oil in the mid 30's and I am still at it today. Many people have different opinions, but I recommend a good 10w30 or 10w40. Any of today's multi grades are so much better than what was available 50 years ago that I think it all boils down to personal opinion.

Multi-grade oil is what was recommended "in the day" (50+ years ago). I use a 20-50 to increase oil pressure at higher temperatures. Some people recommend using oil that contains ZDDP, it can't hurt (a diesel oil such as Rotella).

Tim,

Great info as usual...I would have never, ever guessed that they had a 10w-30 oil in '54. You learn something new on the Stovebolt every day.

Stuart

Rotella ???? Who woulda thunk it? Certainly an excellent oil for diesel engines (been there done that), but good for stovebolts? Heck, why not?

I would be very hesitant to use 20w50 in cold weather. GM always leaned toward thinner oils. Higher oil pressure is not always better. If a gasoline engine was completely rebuilt, running oils such as Rotella and Delo is ok but not needed. However if they have a lot of miles, these oils that were designed for Diesels, but approved for mixed service will dissolve buildup that you really don't want floating around on your system. By the way I sell Rotella and Delo both.

I use 10W30 in my truck and have for 12 years. It is a 235". My mechanic friend whom I trust implicitly says I should use 10W40.

Rotella and Delo400 are rated for both gasoline and diesel engines. I use either in my 261, plan to use it in the 302, and used it in my BMW as well. I don't use it now in my other cars because it doesn't come in 5W20, which is what my Honda and Mazda use.

im using R 15-40 in my two fire trucks, ons gas (270) and the other is a detroit. i run a straight 30 in the dump.

20/50 Castrol here..I too like to do what I can to maximize the oil pressure. no problems however my bolt hasn't been out in the winter sinse about 1984 when I bought a Christmas tree...too cold..maybe after the resto I will..I opened it up this december and it was clean as a whistle.

Keith

Ditto on the Castrol GTX 20-50 because it has one of the highest ZDDP contents out there, even more than the new formulations of Rotella.