I've got 16 5.5hp 160cc Honda powered air compressors and 6 or 7 generators ranging from 3500 watts to 7000 watts.
In the winter I use 5w-30 and summer I use an hdeo in the 15w-40 flavour.
Don't waste your money in synthetics. There is no oil filter so extended drains aren't a good idea.
I change the oil in our equipment every 100 hours. These small motors will end up with fuel dilution at some point in that 100 hours and because the oil isn't pressurized and air filtration is mediocre at best so I've learned over the years that it's pointless to use a synthetic in these machines simply because the 100 hour intervals are easily achieved with a conventional.
And because these engines are air cooled I use 1/4 can of mos2 every second oil change. I've got compressors with in excess of 15000,yes 15000 hours on them with nothing more than basic maintenance.
Our service guy is in awe with the hours on those 2 compressors. He states that a 5.5hp 160cc gx engine will require overhaul at 5000 hours max iirc,usually less because if the operating conditions like high dust and -30 winters,and he sold us the compressors so he knows that 15000 hours isn't an exaggeration.
And the only thing I do different than all the other crews out there is add mos2 every second interval.
The Honda powered generators are the cream of the crop and if maintained semi-decently will last a typical homeowner a lifetime.
Our Honda generators,we have 2,are at least 10 years old and have some seriously hard hours on them. One even siezed on me 6 or 7 years ago.
The low oil alert got unplugged so it got ran without oil.
I broke the crank loose with a pipe wrench.