I use Chevron Delo
https://www.walmart.com/ip/Chevron-D...B&gclsrc=aw.ds for everything in my RV. Engine to Generator. It meets all specifications for all mfgs of any Car, Truck, RV or Genset I know or would own.
It is readily available at any Wal Mart. Does not get any simpler than that.
I will cover any bet that says I will have any issues with this oil over the next 20 years; although I likely only need to go 6 more years on this RV
Note: There are other oils that can be just as good and do the exact same thing, if you tell me that oil and if it is cheaper and widely available,
I will switch today. (Wal Mart's Super Tech is excluded because I like the no blurp blurp pour with Delo; not to mention the branding & packaging
)