Generator Maintenance

I change the oil and filters once per year when I go to Speedco.

I have a GENERAC 5.5 (gas) unit. I change the oil (fossil 10-30) once a year (usually in the spring) along with the oil filter. Both from NAPA.
I changed the spark plugs like 3 years ago only because i felt guilty (the rig is 13 years old now).
I change air filter(s) once every 3-4 years (combination of paper and washable foam).
The most important, IMO is when "in storage" to run the thing every two weeks or so for 1/2-3/4 hour. Don't be afraid to put "hours" on it. They're built for the long haul, so to speak.

I have an Onan 7.5KW diesel generator and change the oil & oil filter every 150 hours or one year which ever comes first and the fuel filter every two years.I change the air filter whenever it looks like it needs changing. I had a 1983 Onan 7.5kw diesel generator on a commercial fishing boat which during the 4+ months of the fishing season the generator ran 24/7. We changed the oil and oil filter every 400 hours and the fuel filter every 750 hours. We rarely changed the air filter because the environment had no road dust etc. When I sold the boat the Onan had over 6,000 hours. It was still going strong. If you run your diesel generator constantly/frequently they will run for a long time. Great product. Most diesel generators will last for a very long time if they are run and routinely serviced.

I would suggest you research your owner's manual and do exactly what is recommended. The people who designed and built your generstor know what is best- much better than anyone who can post anything they want on this or any other forum.

I just change it once a year with the filter. I don't full time and it sits from Dec to Mar.

As you have seen, much of this depends on the generator you have.

A 10kw diesel generator is very different than a 3.6kw gas unit.

Please let us know what generator you have, what year it is,how many hours you have on it AND when was the last time it was run for 40+ minutes at 50% plus load.

Owners manual.

What generator?
It depends on make and model.