This is for the MTX (Manual Transmission) 012 / 01W (5 speed manual)
3 quarts 75W-90 synthetic gear oil (GL-4) (I used redline MT-90, which is "safe for brass synchros, as it lacks the reactive sulfurs found in most GL-5 oils that cause damage").
2' hose that attaches to funnel and will fit into MTX fill hole ( I used ½" ID plastic hose from Lowes - $0.66).
17 mm hex driver - to open MTX fill hole.
3357 security triple square tool to open MTX drain plug.
Oil collection pan.
Warm engine up.
Jack front drivers side of vehicle. Always use a jack stand.
Remove drives side front tire (Optional - I did this to ease access to MTX fill and drain plugs - however it is not necessary).
Remove MTX drain plug (make sure vehicle is re-leveled to remove all of the fluid).
The drain plug is at the lowest point of the MTX in the middle.
Drain old fluid.
Replace drain plug and torque to 30 ft-lbs (could not find torque value in manual).
Remove coolant reservoir.
You can BARLEY see the fill plug looking from the front driver's side of the vehicle to where the drivers side half-shaft enters the transmission.
When removing the plug, you have to orientate the half-shaft so it does not interfere with the hex driver. Removing the tire makes this easier to see, especially the first time, but you can do it from feel.
Remove the fill plug.
I attempted to level the vehicle here to not overfill the MTX. It turned out to be slightly higher at the drivers side (which turned out to be good).
Fill the MTX with the new fluid with the funnel and tube until fluid leaks out. (make sure drain pan is still under fill hole). This required a helper pouring the fluid while I was inspecting for the excess fluid. I had the helper hold the funnel up so the tube was not resting in the fill hole, making it easier to notice the fluid overflow.
The fluid level should be just below the fill hole opening when the car is level. The Bentley called for 2.4 Qts. I ended up putting in most of the 3 Qts. I will open the fill hole to allow more fluid to escape in the summer.
Put the tire on (if off) and remove the jack.
As I mentioned I was not level so I allowed excess fluid to drain as the car became level.
Replace plug and torque to 18 ft-lbs.
Replace coolant reservoir.
I was concerned with some of the postings using Redline MT-90 saying it was hard shifting into first and second when cold. I live in Southern Maryland and the outside temperature when I did this, the temperature was around freezing in the daytime (plus much snow), and have noticed a little more stiffness - probably similar to how it was when new - not an issue.
2003 GL 5 spd