Got a 97 GTP and was debating on changing out the fluid and filter with sythetic. I've had the car for about 3 years and put about 15k on it. I don't know if the previous owner ever did one. I have been being told by a few people that they wouldn't recommend it since I have no issues and the fluid smells ok. They told me that it could cause the tranny to eff up. Then others tell me its ok. I'm not sure what ones to beleive. :|