My dad has one of these very same generators. His is 3 years old. So, I'll comment not just on your UOA, but my experiences as well, since these type discussions are rare (few post up home-use genereator UOAs).
They can run on either LP or NG. NG tends to run cleaner than LP, but both are much cleaner than gasoline or diesel generators. The OEM rec's 10w-30 or 5w-30 or straight 30, depending upon temps. We use 10w-30 syn in his.
I serviced it this summer, rather than him paying the unholy prices to the installer/service company. (Note - everyone has to make a living, but WOW, what a scam those guys run! They provide twice-annual "inspections" for $250 a year, and "service" accordingly. Their idea of service is check the oil level, run the unit under simulated lost-power load, and leave.)
That engine is made by Generac (they make most all of their own stuff). It's a great engine; very robust.
Thanks for the UOA; it helps me know what to expect from my dad's unit. I was going to do one, but now I'm not sure I see the sense in it yet. We need more hours on it before a UOA will make sense.
I seriously suspect that the OEM OCI (2 years) could be pushed further; TBN is good, wear good; you'll not get any fuel dilution; TAN could be known - as suggested. Still, I think 2 years is a conservative figure. When we drained the oil out of my dad's unit, it was still light brown; clearly contamination and insolubles are not a big concern. I fully realize that color is not a scientific method of reviewing stuff, but when it's almost as clean coming out as when it went in, you know that it's fairly clean inside. Look at your wear metals. Some might say that the Amsoil did a better job than factory fill, but I suspect it's just the break in cycle settling down. Not that Amsoil is doing a bad job; just that it should not get credit for the physical conditioning of the engine. Any oil likely would have done "better" on the second UOA.
The wear might seem high on a "per hour" basis, but you have to consider that these things run very little actually under load; rarely do people loose power that often. Most of the hours are accumulated under the "self exercise" programming of the controller. These units will run themselves for 30 minutes once a week, to keep things lube'd and such.
It's important to run a generator under load at least once a year, because the electrical head needs to see some activity. The magnets can actually loose their power if not run in their field cycles for long (years) periods of time. (People that drain the gas let and let their little gas-driven generators sit in the garage for years are NOT doing their electrical heads any favors.)
Service notes: I did a complete service as suggested by the OEM manual (you can get all the details from their site). I even changed the spark plugs and checked valve clearances; won't do that again. The plugs were immaculate when I took them out. Again - the advantage of running NG; clean fuel source. The valves were spot on. (note - the back one is a bit of a pain to get to).
Of note, WIX shows a replacment air filter available, but it must be just brand new, because I can't find anyone (including fleet filter) that stocks it yet. So you'll have to pay the OEM Generac price for the air filter.
It is my suspicion that you could easily double the service intervals of the OEM, and still be fine. They ONLY problem might be the ingestion of dirt. If you're in an area that is currently under construction (homes being built) there will be lots of dust in the air. My parents sub-division is established, so they get "normal" air. Basically, these are very robust engines, that use automotive technology for their oil and air systems, but run a fuel that is way cleaner than gasoline. There is practically no soot/insolubles; there's no EGR; there's no fuel dilution or wash down, because the fuel is truly in a gaseous state, rather than a liquid in small droplet form, etc.
I guess on one hand, I understand why the service rep's don't do much; these things just run clean, and little needs to be done. I would not hesitate at all to run a 4 year OCI; and just check oil level once a year. What is shameful is the $125/visit they get to "service" a unit.
Benjamming - it's up to you, but this is one time when the equipment is almost a "set and forget" unit. Our plan for my dad's unit (now that a complete service has actually been done) is to check oil once a year, and do a full service every 4 years.