Thanks, but my manual from thisoldtractor is a 2002 edition.
I'm not following you re temp range. As I understand 5w40 is meant to cover freezing to "frying eggs on pavement". Yet many prefer going to a higher range of weights.
In my case I don't ride winter and pretty hard to get over 33C but I climb a lot of long hills, sometimes held up following trucks.
There is a semisynth 15w50 Diesel extra Zinc, recommended for bikes, I could get into instead. What do you reckon?
Also, to add to my confusion, one of the old hands posted something about our motor fins being excessive and overcooling.