Your question is two fold- the transmision is seperate from the primary/rear chain oiler system. In the transHarley origanally reco´d 20/50 Premium oil, however you can drian it and use the modern synthic HD Trans Oil. The primary and rear chain oiler are different. Orginal design in 77 was for the engine oil to cirulate thru the primary. The rear chain oiler is adjustable and comes directly off the oil pump. The entire design was very poor and troublesome- oil all over the back of the bike. Most owners have now modified the primary to be enclosed and eliminated the chain oiler as modern o-ring chains don´t need this level of lubrication. The result is a clean bike. The oil system design and routing along with a description of how to do the primary modification is available on-line. When your done you run 4 to 6 oz of HD primary oil.