Yes. SAE30 engine oil is absolutely fine. 20SAE might be a bit thin. You don't need a lot, just each time you start the session, and now and again when you think of it ! You'll know when it needs it : common sense ! I've had an old Coronet CL3 as my mid sized lathe for years now with no problems.
Having read many quotes on various websites, I bit the bullet and bought the stuff from RP on the basis that if anything ever went wrong at least I can say hand on heart I followed the manual to the letter. As it only needs a few drops, the wee bottle should last a while.
I must say, what I find particularly irritating is that the bottle they supply does not have a dropper spout!!
Anyway, onward and upward.