I've been using AMSOIL synthetic products since the late '70s in everything and anything I have that gets lubed. I've never had any lubrication related failures and have achieved some great mileage results. '83 GMC Suburban 6.2L, after 490,000 miles, much of it towing and off road, the original engine and drive train was still going strong but body had such severe cancer, I was afraid it was going to fall off the frame in a sharp turn. I order their products on line and they deliver to my door.
On a trip from NY to Sturgis by way of Canada in 2006, my brother-in-law and myself were both riding 2006 Road King Classics, stock identical bikes, only difference I had Vance & Hines slip ons, he had Rinehart's. He was using HD Syn 3 20W50, I had AMSOIL MCV 20W50. We both had the HD LCD Oil Level, Temperature dipsticks so at each fuel stop we checked oil temps and fuel mileage. I was consistently 10 degrees cooler and averaged 2 mpg better on fuel. Half way there we swapped the dipsticks to see if there might have been a calibration issue but the readings stayed the same. Far from a controlled test so take it for what it's worth. By the way, I'm not an Amsoil dealer, only a satisfied customer.
Tom P.