If you are running flat tappets the
zinc content is a concern.
If you are running roller tappets, any good modern
oil should work, choose a correct wt. for your conditions.
Rumor is GTX scooter
oil has high
zinc but I haven't confirmed this yet.
FWIW, I find the Rotella holds pressure better than the previous "gas"
oil I was running.
YMMV