No oil filter on the generator. Just drop this little green cover on the bottom, remove oil drain bolt to change the oil. Fill up oil to bottom of threads on the dipstick is the approx volume.
Oil change at 150 hrs
Air Filter at 150 hrs (though I usually think they're over cautious on this)
Fuel Filter at 450 hrs.
Oil change at 5,000 miles (if towing, heavy usage) I always change at ~5k.
Oil change at 7,500 miles (regular usage)
Lube chassis points at every oil change.
I'm only at 20k, so I haven't begun to worry about changing the trans fluid/differential, etc. yet.