Canton_Model_A's
Senior Member
Is there any sort of additive I need to put into my oil for the engine to deal with the babbits versus bearings?
I like using SAE 85-140 and STP mixed half and half.
Poured babbitt is a good bearing if properly done. It can take anything that a replaceable shell type bearing can. Modern oils are OK. They used SAE 20/20 in winter and SAE 30 in summer back in the day. Some use 10W30 and some use 20W50 in the modern era but any engine grade oil is OK. I wouldn't use gear lube though. It's made for gears not combustion engines. I only use heavy oil as an assembly lube but I always prime the engine after overhaul and before starting to make sure all the bearings have a good supply of lubricant at start up.
The only thing to make sure you use is oil that is high in zinc. Zinc is needed for the flat tappets in a Model A engine. The amount of zinc has been reduced in most oils as modern engines have switched to roller tappets. An oil that has the zinc levels needed is Rotella T4 diesel and Valvoline VR1 racing oil.