Not disputing you that 62R is a great oil, used it myself for several years in everything including stock class motors but there is no reason to exclude 4T when the motor uses methanol. I am convinced it has an exceptional ability to retain its lubricating properties even with severe methanol contamination.If your fuel is alky always use FHS62R.
If gas, see post above this one.
Idk but I ran Thor until I tore down a motor and saw the affects it left on all the steal parts so a friend talked me into the FHS oil and I have loved the results the oil looks the same going in as it dose going out. Altho I will be getting some of dovers oil and trying it soonWhat is FHS made from ?