Well XTS, I believe......
This has happened to me also, once just the other day. My circumstance was....... I think that my mechanic or the ARMY may have overfilled one of the diffs. The oil to me smells like gear oil. The vents are routed to the air breather canister. I ran her hard the other day. It was 20 degrees and we pulled two semi's and 18 cars from the icey ditch, Bout 8 hours worth. I think the vents ended up spitting some oil into the canister. I wasn't too concerned after I saw that.
-FLASH-