I'm an expert, because I watch Youtube.
I believe the following applies to gas (mine) and propane (yours) generators alike.
Concensus is read the manual. Use the proper viscosity. Do not use synthetic for the break in period. Run under varying conditions of half-load, no-load, and short periods of heavy loads instead of steady conditions.
Change oil after short break in period (probably something like 10-20 hours). Then exercise your generator regularly, it likes to be run.
They suggest 1 hr. per month. I run mine about 45 minutes every 6 weeks on average. My used generator on my '2012 Avenue "b" was running somewhat erratically when I got it. That has smoothed out the more I've exercised it.
Other than exercising it. I only used it a few minutes when camping to run the microwave briefly. That was before my Lithium upgrade, so now it's just to exercise with the roof ac.