The factory service manual calls for the transmission fluid to be changed every 60,000 miles. There's always been a lot of discussion about what type of transaxle fluid to use in the 944 transaxle. The factory shop manual calls for hypoid transmission oil SAE 75 W 90 to API Class GL5 or MIL-L 2105 B, or SAE 80 to API Class GL or MIL-L 2105. What does all that mean? I don' t have a clue.
Better, but more expensive alternatives to the standard transmission oil (IMHO) are Redline Synthetic MTL, Swepco 201, or Mobil 1 75W/90 gear oil. There was some discussion several years ago with regards to Mobil 1 gear oil attacking bronze synchros. However, there's never been anything to my knowledge to support that. Regardless of which of these three you choose, you'll probably notice a marked improvement in transmission shifting and noise, especially when the transaxle is cold.
17 mm Allen head socket / hex key
Jack Stands and Floor Jack OR Ramps
Transmission Fluid (Approximately 2.75 quarts or 2.6 liters)
Drain pan (At least 1 gallon)
4 feet of hose (type not important)
Drive the car for about 5 -10 miles to warm up the transmission fluid.
Raise the rear of the car on jack stands or ramps. I prefer jack stands as they give more room to work around the transaxle.
Using the 17 mm Allen head socket or hex key, remove the transaxle fill plug. The fill and drain plugs are located on the left hand side of the transaxle. The fill plug is the upper plug. It's important to remove the fill plug first because if you drain the transaxle first and then can't get the fill plug out....... Well, you get the picture.
It's also a good idea to warm the new transaxle fluid before you put it into the transaxle. Heating allows the fluid to flow more easily into the transaxle. Try placing the transmission oil containers in front of a halogen heat lamp for about 20 minutes. DO NOT heat in a microwave.
Place a drain pan under the transaxle below the drain plug.
Remove the drain plug to drain the transaxle.
When the transaxle is completely drained, install the drain plug and torque to 24 Nm (18 ft-lbs).
Route the hose over the top of the left rear wheel, over the top of the exhaust, to the fill hole on the transaxle.
Using the funnel, pour the new transaxle fluid into hose and into the transaxle until the fluid level is just below the bottom of the fill hole (6-8 mm). Personally, I fill to the bottom of the fill hole.
Install the fill plug and torque to 24 Nm (18 ft-lbs).