I just had this conversation with my son Daniel (Mini-Cooper and BMW tech) regarding my 2002 S40. I've been monitoring the trans fluid level because of some minor seepage at one driveshaft seal and found that it is was just low enough to require a top-up. I haven't had to add fluid in the 4 years I've had the car. The owners manual calls for fluid with the 3309 spec as already mentioned by a BB poster. This fluid is used by many Japanese cars - and in particular Toyota which also uses the Aisan-Warner transmission. I already had a quart of Castrol brand ATF labeled for use in Honda, Nissan and Toyota so that's what I used. I find it odd that nowhere in the owners manual is there a word about the trans dipstick - where it's located and how to read it. I think newer Volvos do not have a dipstick and maybe an older manual would have info. I have a 2001 manual as well as the 2002 - no mention -- not even on the "under the hood" page showing where fluids get checked/added. -- Dave