What is the best or most used gear oil for shaft drive '04 Meany?

I don't remember the weight, but I just use the walmart brand (Supertech) synthetic. I change it once a year with my oil. I also put in a magnetic drain plug from gold plug llc. The best oil for anything you ride or drive is the oil that is changed most often. I have been using shell rotella 5w40 for years in all my bikes.

A buddy of mine who works in a motorcycle shop and does side work out of his own shop recommended to me valvoline dura blend 80w-90 gear oil for mine. I've been using it for several years know and works great.