the oil on the pipe and cured is good ,its like seasoning your camp cook pot if you use a high temp oil find one as clear as you can just keep rubbing on after cleaning the bike after a ride we did it back in the eighties in england very damp place you only had to go in the house to defrost you fingers after washing your bike come back out and your trick pro curcuit pipe was already turning ,mi old grandad said ,rub a bit o oil on it son and it never went rusty again it dose brown up a touch down low but thats character