I use Mobil 1 5w20 for V10 (need 16 mm socket) & used 30 weight for first change on generator, thereafter, Mobil 1 10w30. BTW, you need a torx t-30 to remove the access plate screws & 9/16" socket for the drain plug. If you don't tell anyone, I actually evacuate the oil from the generator crankcase through the dip stick hole like I do with my inboard boat motors.
2013 Thor 29.2 (HaRVey), interior bike rack, CHF, DIY rear panhard bar, ventilated generator door, 2018 Chevy Spark toad (Sparky)
“It is a mistake to allow any mechanical object to realize that you are in a hurry.”