Kohler K241-S Oil Bath Air Filter

[oldnugly 2]

My 953 has the oil bath air filter. This is the first oil bath type I've worked with. I understand there's a sponge type piece in it that can be cleaned. My question is, what kind of oil should I put in it? Thanks :thumbs:

[WH854 44]

Back in the fifties and sixtys we used non detergent 30 weight

Chas