which Penrite Full Syn are you using?
HPR15,15W-60 I've been using it since it ran out of warranty at about 42,000kms (going on memory, it was a shop demo bike with 8,000kms and 6 months use on it, so I only got 18 months warranty), and I started doing my own servicing.
I had a touch of clutch slip and slight squeal under max power while it was running on genuine oil and shop clutch adjustment, which disappeared on the Penrite. I always thought the Bris Vic shop had the clutch cable too tight after servicing, so run it with a touch more freeplay now.
I know Penrite don't recommend it for motorcycle use, which I think probably translates as wet clutch use, but no clutch problems yet, although it's a pretty standard motor. With cams and a fuel controller it might, but that's not happening soon.
My 1990 1200 Sporty did start clutchslip after cams and an S&S, but running Barnett plates, Screaming Eagle spring and an extra steel plate keeps it coping. It did cop a lot of abuse running 1/8th mile dirt drags for a while, and still has a brass plate off a trophy riveted to the aircleaner "Top Street Bike Aratula 1990".