Generator opil change

I use Mobil 1 5-40 turbo diesel in the Generator and the 5.9 Cummins. This would be my preferred oil for a Onan Marquis 5500 gas generator.
Bill

I use Shell Rotella 15/40 for both the Cummins 8.3 engine and Onan 7500 diesel Gen set. Buy at Wallmart for about $13/gal.

Hey Craster,

My old man swore by Marvel Mystery Oil. He was an Operating Engineer for local 150 and maintained many of their gas operated welders, pumps and various mobile equipment in Northwest Indiana.
I always thought it was just transmission fluid in a high priced can.
Glad to hear it's still working out there.

Pete :P

Buy the cheap Extra Guard Fram oil filter, you get a cheap oil filter. Buy their more expensive Tough Guard filter and you get a good oil filter.

By the way, I have a 1990 commercial lawn mower (Scag 72" cut) with a Kohler air cooled engine. Still running strong with nothing but Fram filters and Mobil 1 oil.

I wouldn't put a Fram filter on my lawnmower. Do a little research on Fram filters. (Just my opinion. Not trying to start a war here.)
My gennie only holds 3 quarts, so an extra couple of dollars for synthetic in this case is worth the extra potential of the oil.
But as opined by the Supertech users, any certified correct formula oil will suffice under recommended service intervals.

I use the Fram oil filter and the Walmart Supertech stuff for both my Onan generator and Cummins diesel. I'm sure that the motors will outlast the applications that they powering, so stick with the reasonably-price stuff.

I'll save the Synthetic oils and OEM filters for my BMW. My 7-series Bimmer contains a complicated beast of an engine that is not nearly as forgiving:(

With an air-cooled engine, using a synthetic oil from a reputable supplier is a very good idea. A synthetic oil will handle high temps better.

I' using Mobil 1 Turbo Diesel 5w-40 oil (also rated for spark engine use SL and SM).

It gets a lot of downtalk, but I love generic supertec oil from walmart. I have used it for years and years and years now. I have it in my go-karts, chipper engines, generators, lawn mowers, motorcycles, and several other engines that I have - and my class A and class C. It is NOT the best oil that exists, but it still gets a solid A for a grade on the report card from me. It is often packed by mobil. It is very inexpensive too. I also love marvel mystery oil. I put a couple of drops of that in my gas and oil. Just my .02. Otherwise my next choice is take the plunge and use mobil 1 sythetic.

Just changed the oil in my diesel QD 7500 yesterday using Delo Synthetic 5W40 with a Bosch filter bought at AutoZone.
Rotella, Delvac and Delo are for diesel engines so are probably not recommended for your gas unit.
Seeing that your unit it gas, I'd use Mobil 1 synth at whatever viscosity Onan recommends.

I have used the Fram filter and Rotella since I bought this thing and I run the generator a whole lot, year round. Since we go to the beach a lot things get dusty down there so, I change the filter at every change and blow out the air filter.