The Stovebolt Site Forums The Shop Area Engine Shop What oil to use

Good Morning,

I have a 1941 Chevrolet Howard Cooper fire engine that I believe is based on a 1 1/2 ton chassis, not sure, cannot find the VIN so looking for other numbers. The manual calls for SAE 30 oil, what are others using in these vintage engines?

Thanks
Tony

Hello, Tony,

10w-30 or 10w-40, or 15w30 or 15w40 (I like Rotella T oil)

No need for synthetic oil.

The only concerns about the switch-over from older non-detergent oil to modern detergent oil is that detergent oil keeps more "junk" in circulation (to be removed by an oil filter - if you have one). Non-detergent oils tend to allow "junk" to drop out in the oil pan. There is a possibility that after switching to detergent oil, some of that "junk" will go back into solution.

Some people advise you to remove the oil pan and clean it out (and clean the oil pump "pickup" screen) when switching over from non-detergent to detergent oil. Of course, if you have one, change the oil filter (and, canister) at every oil change.

I use Rotella SAE 30.
Not sure of benefits or drawbacks to using a multi weight oil, like Tim suggest, when a straight weight was originally specified and worked fine for years and decades.

Tony, that's a really neat truck and a neat story (that you used to be a firefighter in an identical truck). I'm sure you'll have fun working on it and giving your granddaughter a ride! I gave my 5-year old grandson a ride in my '51 half-ton and it scared the holy crap out of him. He's done with that truck, for now.

In the summer my 1951 216 gets 15W40 diesel oil, winter it's 5w20. I'd use 15w40 year round except for the fact that when the temps get into the 20's it pours like thick molasses. Not sure how the oil slinger would like that.

Now that said, 15w40 has been in my Dodge Cummins diesel year round for 20 years and at 275k miles, all's still good.