Hello, I have decided to go with motor oil for my manual transmission rather than gear oil. The T-496 is known for under lubrication at the upper levels of the housing and I have read a lighter weight engine oil like 10w30 is best to solve this. However, would an even lighter weight oil work any better? Would I better off with something like 5w20? Or maybe a lightweight manual trans fluid? Another solution posted online is to add a 90 degree elbow to the fill port, however my fill port is on top of the housing not the side. Did IH move the fill port to the top as a way to raise the oil level or am I missing something here? My lineset ticket says I have a T-496 in a RA-199 housing. I attached it below. Thanks for any help.