I've got 15 5.5hp air compressors,and iirc 8 or 9 generators now. This past month I decided to use up some of the jugs of 5w-20 syn I had laying around. All Quaker State Ultimate Durability and Pennzoil Platinum. Everything has been easier to start in the mornings with 5w-20 in them,and with ambient temps of -20 as a high I'm not worried about anything overheating.
Up until now I did use 5w30 supertech bought in 5 gallon pails from Walmart in the winter,and rotella 15w40 in the summer. Mos2 added to every second oil change.
I've got compressors with over 10000 hours on them,never had anything but oil changes and pull cord replacements. I change the oil in all our equipment every 100 hours which is roughly 2 weeks.
The only reason I change the oil at 100 hours is fuel dilution,especially now with winter temps and running longer with the choke engaged.
I've got so many compressors and generators now I can't keep up with what's in and what's going out.
I use amsoil air compressor oil in the compressors. And only amsoil. That stuff is amazing. At -40c the stuff is still liquid and makes the compressors much easier to start,and gives me the warm fuzzies knowing the pumps are actually getting lubricated because of the splash lubrication design.
I haven't used anything special in any of our equipments engines other than mos2 every second change. They get the cheapest oil I can find,changed at regular intervals.