My son worked for Rob Muzzi for 23+ Yrs, Rob was the Kawasaki factory road race team owner and manager for many, many years, they also sponsored his NHRA Pro Stock bike team for several years. They where revving those 750 and 1100 CC road race motors over 14,500 back then
My son introduce me to his head mechanic back in the mid 1990s, they where using Motul synthetic racing oils only in their bikes back then, I use to see it in the race shop until Rob retired
I don't like synthetic oils for my own reasons based on results from dyno testing and the synthetic oils leaking, seeping, weeping, through many American made gaskets for our old Mopar motors, pure oil based oils don't leak through them
Mobil Oil Corp was sued by the Contentinal (SP) Aircraft Engine owners assoc. on their Mobil AV 1 synthetic aircraft oil because it wouldn't stick on the camshaft lobes and lifters when those motor would sit for more than a week without running. They won the law suit( a bunch of money, a BUNCH) and Mobil quit making and selling that oil right after the law suit was settled
I had used that oil for over 7 yrs in my Piper Comanche 250 and it would not hold gunk in the oil, it would leave deposits all over my airplane motor where it would sit and puddle, I had used Shell aircraft oil before that and that motor had no gunk in it anywhere when I bought it, I had the plane inspected thoroughly before buying it due to it had sat for over 18 months without flying, I was able to remove a lot of the inspection panels and all the rocker ram covers to look inside that top end, we did a leak down test and cleaned and gapped all 12 spark plugs. It turned out to be a very good air plane
I flew it for 15Yrs and a little over 900 hours before it got totaled on the ground by a hail storm here in Bend, OR d
I think all the new cars and H.D. trucks come with synthetic oil in them from the factory now