Hello all. I am looking for some advice on oil for sintered bronze bearings in an old motor(1/2hp). The manufacturer's plate says to add 15 drops of non-detergent SAE 20 oil every year. On a plain bearing with no force-feed lubrication, is detergent(motor) oil going to harm the bearings/journal? The only comment I have found online other than do/do not use, is that the detergents may dissolve the insulation on the windings. Another comment was that if put in a gear box, detergent oil will foam. I had a friend who used GTX20W50 in his car gearbox without any issues. I have a bench grinder with a worm drive for a wet wheel. I put a clear cover on the drive and put gearbox oil in. It foams away merrily!!

I understand most forums are run by self -styled experts( e.g. bobistheoilguy)who have little to no actual knowledge.