I have wasted a clutch with my first and last try with synthetic auto oil. Its not a myth. Teflon and other friction fighters are designed to bond to metals. Standard oil is good for me. Clutches last a long time with basic oil. Cheaper changes too, Polar
Car oils just aren't beefed up with the extra high pressure additives, intended for use in a transmission. Not sure why everybody insists on using them in their bikes???
Sure the OLD honda and KX manuals state it.. BUT thats before the advent of good motorcycle specific oils with shear strength, and good friction modifyers.. the demands of a motorcycel gearbox are a far cry from what auto oil is designed for...
If you want to argue this.. I have manuals for my old Bultacos that tell you to use DRAIN OIL out of your car for mix in the fuel.. YES USED DRAIN OIL... know why? It was fine back then... but times change.. and oil changes.
Also stating that by using synthetic auto oil, caused your clutch to slip, so all synthetic is bad? Well auto oil is differant, not designed for clutch, Motorcycle synthetics are, and have the friction modifyers to make them work properly.. and not swell the clutch plates.
You cant blame all synthetic oils for User error...