[Handyhiker]

All 3 have low oil pressure shut down, so that means they all have an oil pump. I assume all have a filter but not sure. I think the differences in these are not a major concern. I would pick the one that has the features I want and not over think the whole process. They are all close enough that I don't think it really matters.

 

[Handyhiker]

Silly me, I read all 3 and ALL say low pressure shut down, I never said anything about a low oil level shut down. The second one says it has a spin on filter, cool. I have and use an Onan 5000 watt without a filter and have several thousand hours on it. It still runs great! Oh, did I mention it is a 1973. Again, I really don't think that any of the 3 are that much better or worse then the others. It is going to matter more on how they are taken care of then anything else.
And my apologizes to all and especially you, thehandyman1957, with all the generators I have worked on and owned and own, I thought I knew some, I guess not. Guess you should only take advice from a gen guy. (So we can see that the gen guys do think it makes a difference.)