you can run either reg motor oil ?, or same gear oil that goes in the front and rear differentials ?, 80w-90 hybrid gear oil. full synthetic is what I run with 80w-90. reason: there is no clutches inside this area to worry about. if it was your engine ?, then you must run oil made for wet clutches !..but this is not the case . if I remember right ? it tells you on the front side of the case I think ?.