Im considering doing a drain and fill on my trasmission. I've done a lot of searching and I've found a lot of conflicting info regarding what type of fluid to use in an Automatic transmission on a 2000 S40 1.9T and I hope someone can clear it up for me. The manufacture year on the car is 1999, the owners manual says Dextron III but I've read in quite a few places that there's different fluids recommended, including Toyota type T-IV, Dextron III and JWS 3309. Is the manual wrong, are these fluids interchangeable? Even on an import car parts website it lists dextron III and jws3309 as compatible to my model.
Any help would be appreciated.

 

What is your intent here? If the manual says Dextron III (which it does - Mercon is the same, Dextron is the GM name, Mercon is Ford's for the same spec), that's pretty easy to find. AW transmissions did change their specs over time, so my 95 850 calls for 3309 - which can be expensive when buying OEM from Volvo, thus people shop for the Toyota T to save some bucks. Given Dextron is used in many models, its easy to find. Transmission oils are not the same as engine oils since the transmissions are designed for specific friction coefficients to work properly. Going off spec is a bad idea as it can lead to unpredictable results.

 

Thanks for the response. My intent is to determine what the best option is for transmission fluid type in my S40. Since I'm doing a drain and fill, which only does approximately 3 quarts at a time, I was concerned about using a fluid that wasn't compatible with what's already in the trans from the factory.