I have a Onan 5.5 Gen and I just checked the last time I changed oil! It has been a year and 8 months and 14 hours! Should I still change oil and filter with that few of hours ??
One thing to note about changing the oil in the 5.5 JAB Onan is that the second quart goes in real slow. I do two things to help.
Fill the new filter before installing it (always a good idea anyway I think)
Screw the oil fill cap/stick in and turn the engine over for a few seconds to circulate the oil up into the engine then start adding oil again. I usually have to do that two or three times.