ok so by looking at my former thread im deciding to change the gear oil. now i believe when the dealer that i bought this viggen from put the oil type gear oil in it was a tall AC-Delco bottle. now when i called the new Saab dealer here in Ottawa they said its just a drain and fill. now i have been reading alot on this and there are lots who say to flush it with 1-3 liters of Mtf-0063 then do a final fill. Any ideas on what i should do? flush and fill or drain and fill?