What happens if you put 90w in the transmission but haven't replaced the mainshaft bearing with the sealed set? Replacing the bearing with a sealed unit is something I'd like to do, but I'm hoping to ride for the season before tearing into the transmission, but I don't want to ride it if the oil is going to leak everywhere... What's the word?
On the 4-spd? Never. Adding them is a home remedy.5spds are built to run in oil.