Hi All,

I'm relatively new to this. I have a 1950 Chevy 3800 with the 216 6 cyl. It was purchased from an estate so there is no prior knowledge of the previous owner's maintenance, other than he was purportedly a "mechanic" and owned the truck for nearly 40 years. I want to change the oil in it but I was wondering what I should use since I have no idea what is currently in the engine. I've read about being cautious with detergent oils in old engines.

My hunch is that the oil currently in it is a modern detergent oil since I can peer into the top of the engine via the oil fill hole, and it appears to be clean. I don't see any black sludge like we used to in the old days with the non detergent oils and mileage.

Also, should I use a straight weight or multi viscosity oil?

Thanks for any and all advice.