It can't piossibly hurt to try Dino based oils *BUT* ~ 20W-50 is too thick for a Tiddler engine and way too thick for a wet clutch in any case .

So , go down to your FLAPS and buy one quart of Dino based 10W- whatever oil that's Diesel rated and do a hot oil change .

Be sure to follow my clutch adjustment regimine too as a 1/8 turn of the adjusting screw can make a big difference .

I hope you've at least once cleaned out the centrifuge .

Shiny bores with visible cross hatch means improper ring seating and higher oil usage than could have been had .

FWIW , once the cylinder glazes , it'll last forever like that .