onan generator oil change

[jpolito]

about to do first oil change on onan generator (20 hours) on our Greyhawk. Information is extremely hard to try to get from anyone about oil. even owners manual does not address synthetic. I use Mobil 1 full synthetic in all of my vehicles, does anyone else use this of the correct viscosity (mine says 15w40) in your generators? Any stories, thanks.

[bdreinv]

Might check with Cummins, Honda did not want us to use a synthetic!

[jimp]

Look on the generator itself. I think IIRC I used straight 30w oil per manual .

[NC Roamer]

I use their OnaMax 15w-40 oil. That enclosed generator shoulders quite a load in hot weather to run the A/C. I figure that multi-weight oil might help it some.

[txhood]

Mobil 1 15w40 in mine

[edatlanta]

I use Rotella T4 15W-40 diesel oil. It is on the approved list for my Onan 5500 and since it is the same oil I use in my truck I only have to keep one type of oil on hand. 188,000 on the truck and 470 hours on the Onan and neither one has ever used any oil.