I use Shell Rotella 30W diesel oil; the previousowner mentioned that the zinc in the oil helps with the babbit bearings.
Hey Jynx, if you look for previous posts regarding motor oils you will find enough opinions to keep you busy for days. At the risk of being labeled a heretic I doubt that you could find a motor oil for automobiles that would not be adequate for a Model A.
Hello.
I am not sure if I have understood the core question correctly.
For vintage cars, a low viscosity can have the disadvantage that the shaft bearings leak leaking oil. Otherwise, a multi-grade oil is always better than a single range.
The most important is the API classification. Because of the non-ferrous metal compatibility. You should not go higher than "SC". Petrol engine oil API SC has anti-corrosion inhibitor, detergent cleaner, HD heavy duty additives. That is enough!
However, the oil still has to be changed many times (max. <1000 miles) because it runs without a filter and only then can the abrasion chips be
taken out.
Good evening!
These motors are unsuitable for low viscosity oils. The large installation tolerances require a thick liquid oil to maintain a hydrodynamic lubricating film in the crankshaft bearings.
In addition, a low-viscosity oil leads to increased oil consumption and the combustion residues in the combustion chamber got too much.
Hey Jynx, if you look for previous posts regarding motor oils you will find enough opinions to keep you busy for days. At the risk of being labeled a heretic I doubt that you could find a motor oil for automobiles that would not be adequate for a Model A.
I agree with that. Engine oils in the day were not very good. Even the cheapest oil available today is light years ahead of anything they had back then.
I use what ever oil is on special at the shops - usually 20W50. With a 180F thermostat, the engine temperatures are high enough that it does fine.