Onan Generator Servise

[woodspinner]

I am new to using an Onan Generator and just bought one. When checking on what type of oil to use I found information that was questionable so I contacted Cummings Support and here is their report as of 8-31-21.
They do not recommend any synthetic in their generators. They said to use regular oil at 15-40 grade, non-specific to the location in the lower USA.
Hope this helps

[DonC757]

My 2019 5.5 calls for straight 30W if temperatures are above freezing. Picture from my owners manual. By the way straight 30W is getting hard to find.