Easier than an oil change! The Factory Service Manual recommends this action every 36,000 miles or 3 years and suggests you use "hypoid transmission oil SAE 75W90 to API Class GL or MIL-L-2105B, or SAE 80 to API Class GL-4 or MIL-L-2105". GL-5 was later recommended for use in all Porsche transmissions through a series of Tech Service Bulletins and FSM updates. The gearbox fill capacity is 2 liters (2.1 quarts). Most shops and seasoned owners will recommend that you use a higher grade or synthetic gear oil like Swepco(201) or Red Line (75W90 for LSD and 75W90NS for non-LSD).
Jack up the car level with all four tires off the ground. On the rear left side of the transaxle will be two 17mm hex bolts. The top is the fill and the bottom is the drain.
Before removing the drain plug, check to see if you can remove the fill plug. If you can then it would make refilling impossible... these things do cease. You may need to "wake-up" the threads by tapping on the Allen wrench with a hammer - not too hard. If the plug is hard to move, use a releasing agent such as WD-40, PB Blaster, or Aerokroil. If it is still hard to move you may need to use heat - be very careful.
Remove the drain plug to remove the old fluid. You might want to screen it to check for particles (pieces of your gears!) if you suspect a problem. Symptoms of excessive ring and pinion or synchronizer wear can be diagnosed at this time.
Replace the drain plug. Torque to 18 ft lbs.
Add your new fluid through the top until the level is 6-8mm from the bottom of the hole. You can use your finger to "feel" the level. For cars equipped with an external transmission cooler, the fill level should be a bit higher to allow the cooler to refill completely. DO NOT OVERFILL! 968's have a redesigned case that requires the fill level to be even with the fill hole (fill till you spill).
Replace the fill plug. Torque to 18 ft lbs.
Note: Fluid will drain much more effectively if the transaxle is at normal operating temperature. A 10-minute drive just prior should suffice.
If you are buying your fluid by the gallon then you may need some sort of device to get the oil up there. There are several pumps on the market to accomplish this - the most effective being a MityVac. Some regular gear oil 1 quart containers will fit perfectly up there, such as Redline.
You should always strain the fluid you remove from the transaxle to check for "particulate". You can sometimes avoid component failure by examining what the fluid carries out... or, at least know that the end is near. Coffee filters work okay, but they're really too dense. I use old white t-shirts. Just run the fluid over the material before it enters your catch can. This is good practice for any fluid coming out of the car... engine oil, coolant, ps fluid, blinker fluid, etc.
For more information on gear lubricants and recommendations, click here.
Tools: Floor Jack, 4 Jack stands, 17mm Allen wrench or socket, drain pan, fluid pump (optional)
Credits: Skip Grehan
> Window Express Kit Installation
> AC Delete
> Accusump Installation
> Adjustable Ride Height Kit - Paragon
> Alternator Replacement
> Brakes, front - 924S, 944, 944S
> Brey-Krause Strut Brace Installation - 944
> Camber Plate Installation (Paragon)
> Clock/Bulb Replacement, digital, Late 944 and 968
> Clutch Replacement - Part One
> Clutch Replacement - Part Two
> Clutch Slave Bleeder Valve Remote
> Control Arm Bushing Upgrade - Weltmeister
> Control Arm, Front - Info
> Coolant Flush
> DME Chip Installation
> Dash Replacement
> Engine Identification
> Engine Production
> Fuel Level Sender
> KLA Strut Brace Installation - 924S, 944, 968
> Koni Strut Conversion - 8641-1414S for late 944, 968
> Motor Mount Replacement
> Odometer Gear Replacement - late 944
> Oil Cooling, Auxiliary
> Oil Pressure Relief Valve
> Oil Pressure Sending Unit Replacement
> Rear Ride Height Adjustment
> Porsche Chronology
> Rear Spring Rates vs. Effective Rates
> Rear Wheel Bearing Diagnosis
> Rear Wheel Bearing Replacement - 924, early 944
> Rear Wheel Bearing Replacement - late 944, 968
> Ride Height Measurement
> Rod Bearing Replacement
> Shift Lever Rebuild
> Short Shift Kit
> Throttle Position Sensor
> Sway Bars - Info
> Torque Tube Rebuild
> Torsion Bar Replacement
> Transaxle Fluid - Info
> Rear Sway Bar Installation
> Transaxle Replacement
> Heater Clip
> Window Regulator Replacement
> Seat Back Brace Installation Instructions
> KLA Strut Brace Installation - 968/944 S2/944 S