Whats so special about Onan generator oil
Just doing a service on my generator (5500 Marquis model 5.5HGJAB-1038D). Bought plugs and filter, but they wanted $15 a quart for the Onan SAE 15W-40. Thought maybe I could just get it cheaper at an ...
Forum Discussion
Interesting reading as I am trying to decide what oil to put in my 2012 year Onan/Cummins gas generator. I have Rotella 15/40 in my garage but didn't think a diesel oil would be good for a gas engine, I couldn't find straight 30 weight in synthetic so I bought regular 30 weight. So it's either regular 30 weight, Rotella 15/40 or synthetic 10/30. What to do, what to do? The manual says to use the 15/40 or 30 weight for the temp range in my area but never mentions using synthetic. My gut feeling is go with the 10/30 synthetic and call it good.
