I have read up on the plus side of using synthentic oil, but concerned about switching with 46k on the engine. I've used conventional in every HD I've had  with no bad effects. What is the down side, if any, if I switch with this many miles on the engine? A friend switched and had serious problems with leaks, was this just fluke or is this sort of thing common with higher mileage motors? Will oil pressure be affected, will engine noise increase? I have changed the oil every 3k like clock work and the bike runs fine, I don't want to make problems for myself, but want to use whats best for the engine. Having a difficult time with this, any help will be appreciated.