sounds like a lack of oil mate see if u can get any fault codes out of it if there is any that is .... get the trans nice and warm like after a long drive if possible keep engine running and put Netural or Park, and pull the dip stick out and check the level, that is if tha vr6 auto box has a dip stick im guessin it would do but never worked on one .... if u got a owners manual should tell u in there ...