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manual transmission gear oil DIY service and fluid replacement-mk4 VW-Audi
DIY drain and refill manual transmission gear oil for Jetta, New beetle, Golf (4th generation cars and similar Audi)
This article shows how to change your manual transmission gear oil on VW TDI Jetta. The change interval is as needed.
If your shifting is getting more difficult, it could be due to low or dirty gear oil. Your gear oil should be regularly changed. Note - gas VW need a torx bit, VW diesel TDI use a regular 17mm allen for the drain and fill plugs
Related links: 1000q: how to adjust your shifter mechanism.
17mm allen wrench
gravity pump (siphon), or compressed air tank, hose and nozzle, or some other pump
2.0 Liters of gear oil (the transmission and differential share the same oil)
Basic kitty litter or driveway spill absorber
If your car is a late 99.5-2003, use 75w90 synthetic gear oil (VW# g 005 000 is the .01 liter size) (VW# g 00500005 is the 0.5 liter size).
If your car is a pumpe duse and is 2004-2005 you can use 2 types: (VW# g 060 726 a2 is the current synthetic oil (thanks for the tip heychris!), g 052 171 a2 is the old synthetic oil) (VW# g052 726 a2 is the mineral oil).
If you have a choice, use the synthetic oil. For all cars, G70 supercedes all previous gear oils.
VW is constantly changing their gear oil spec for whatever reason and contradicting themselves so just use whatever you want as long as it's GL-4. The part number for G70 is G 070 726 a2. Most VW manual transmissions should only use a GL-4 gear oil, not a GL-5 gear oil like Mobil 1 75-90. Many people have success with Redline MTL or MT 90, or Royal Purple Max gear. I have tried a few different gear oils including the OEM VW synthetic and found that I prefer Redline MTL since it's slightly thinner and makes shifting easier, especially in the winter. Here is a link where you can get Redline MTL.
From thickest to thinnest, here is a list of gear oil viscosity at average working temperatures. Redline MTL is slightly thinner than some OEM VW gear oils which helps it shift better in cold climates.
VW G50/G51 GL4, Redline MT-90 75-90 GL4, VW G052-911, Redline MTL 70-80 GL4, VW G-052-171-A2, VW G-055-726-A2
Engage the parking brake, chock the wheels, jack up the car using the factory jack points, rest car securely on jack stands, and make sure the car is safe and secure before doing anything else. Note that the car must be level, otherwise the fluid level will not be accurate. I use wheel blocks to raise the car as an extra level of safety in addition to jack stands as suggested in 1000q: mechanics tips or 1000q: making wood blocks.
Draining the fluid
Engage the parking brake and put the car in gear, jack up the car using the factory jack points, rest car securely on jack stands, chock the front and/or rear wheels as necessary, and make sure the car is safe and secure before doing anything else. Remove the plastic splash shield under the engine. If your car is lowered or you want an extra level of protection for the aluminum oil pan you can add a metal skid plate. See 1000q: skid plate for more details.
Clean the area around the fill and drain holes or else dirt can get into the transmission fill hole.
Use 17mm allen wrench to loosen the fill hole plug, circled in yellow below. Always loosen or remove the fill hole first to make sure that you can refill the transmission after draining.
Loosen drain plug, circled in green. Put a catch pan under the drain plug, remove the plug, and let drain.
Here is another angle.
Below is another picture from a different view on a mk3 VW. It's the same basic transmission except the power steering line is routed differently.
Refilling the manual transmission gear oil
Clean the drain plug and put it back. Torque to about 20-23 ft lbs.
Refill with 2.1L. Once you have added enough gear oil, it should start to drip out of the fill hole (assuming the car is level). Stop and put the cleaned fill plug back. Torque the plug to about 20-23 ft lbs. If you foamed the oil at all, add slightly more fluid to the transmission to compensate for the foamed oil (the foamed oil contains air).
There are a few ways to get the fluid back in. You can use a gravity pump or siphon, where the bottle is higher than the fill hole and connected with a hose. You can also use a hand pump designed to force fluid out of a container. The easiest method on the TDI is to use a funnel and hose, and snake it into the transmission fill hole from above. I feel that this also wastes the least fluid. Below is a picture of the yellow tube going into the fill hole, sorry that it isn't that great but it's not terribly interesting and if you got this far you know where the fill hole is. (*your car may look different)
Another method is to use compressed air to force the fluid into the fill hole. It's not possible to use a funnel on many cars so I originally made this for my Audi and on other cars. To use the compressed air method of adding fluid, take a compressed air tank and regulate the pressure down to a reasonable amount, just enough to get the fluid flowing. If the pressure is way too high, the bottle could pop, so start low and then increase the pressure if the fluid isn't moving fast enough.
Use a short length of hose, just longer than what is needed to go from the bottom corner of the bottle to the transmission fill hole. Make sure the hose has at least 1/4 diameter, otherwise the fluid will have a hard time flowing through the hose. If you can't breathe through the hose, it's too thin.
Poke a hole slightly smaller than the hose in the cap (smaller is better for a tight air seal), and a small hole (again, smaller is better) in the top of the bottle, marked by the green arrow in the below picture. Obviously the air input hose has to be above the fluid level or else it will leak out. Now stick the hose into the cap, making sure the hose goes all the way to the bottom. Make sure that the hose goes all the way to the bottom of the bottle otherwise you will get just foam instead of fluid. Too much foam will fool you into thinking there is more fluid than is actually in the transmission. If this happens, let it settle down and overfill it slightly. Also make sure the hose has a large enough inside diameter because thin hoses will transfer fluid at a snail's pace. Since a picture is worth a thousand words, here you go.
Now press the compressed air nozzle into the hole in the top of the bottle marked with the green arrow in the picture above. Warning! Do this step last because you may accidentally press the trigger on the compressed air nozzle before the hose is in the fill hole. If this happens, your expensive fluid is now all over the ground. Apply gradually increasing amounts of pressure until the fluid is gone. If the bottle stretches a little that is okay. If you think it's going to pop, stop applying pressure. I put my gloved hands around the bottle cap and nozzle to prevent any fluid from hitting me in case the bottle cap blows off. As always, wear protective safety goggles.
Like this tip? There are many more tips for the mechanic at 1000q: mechanics tips and garage organization.
Note that the fill hole end of the hose has a coat hanger bent into an s-shape (so it stays in place) with a hook at the end. I did this so that I could use the same hose for both manual and automatic transmissions and to minimize dripping at the end of the hose. Some Audi transmissions have a cap on the fill hose which requires a 90o bend at the tip.
Once the gear oil comes out of the drain hole (assuming the car is level) or you have added enough gear oil, stop and put the cleaned fill plug back.
When you go to the next bottle, just poke another air intake hole in the next bottle and transfer the cap. Don't let the hose touch the ground because it will collect dirt. If it gets dirty just thoroughly wipe it off.
When putting the fill and drain plugs back, you can wrap the threads once or twice with teflon tape to help ensure no leaks.
After you're done, hang the hose with a paper towel or two on the end and let it drip dry.
If you spilled some gear oil during this procedure, wipe it up with paper towels. Then sprinkle kitty litter or driveway spill absorber and step on it to grind it into the stain. After it sits and absorbs the oil, sweep up the gravel/dust. Most local auto shops or garages will accept used engine oil or gear oil for free but if you can't find a local disposal, earth911.com can search for a local waste disposal. You can also use a large piece of cardboard to act like a placemat to avoid small stains from leaks.