Just performed the annual oil change on the installed Onan generator (even though it only had about 20 hours on it since last year). I need to buy some more oil and had been using OnaMax but will any good quality 15W-40 suffice?
Oil is oil.
I use the cheapest oil I can find.
any 10W-30 oil is best all around for most climates.
I use 10-40. I can use it in my RV engine, my generator and my motorcycle.
I usually get house brand from wherever I go.
O'reilly's has some for a decent price.