How to Change or Flush Transmission Fluid: MKIV, Jetta, Golf GTI, Beetle
Volkswagen Transmission Flush DIY
Hello friends, this is a quick and easy DIY showing you how to change out your "lifetime" VW transmission fluid. I think my local dealership wanted $130 to do it, but you should be able to get the job done yourself for about $20, including the 17mm Allen-head socket. This DIY should be the same on all manual MK4 VWs or New Beetles. I know my 1.8T and the "2.0 slow" are identical for this purpose and I believe the VR6 is the same.
This DIY will not work if your car is automatic. For automatic cars you need to warm them up to a certain temperature and do all this other special stuff (that's what you get for not learning how to drive a real car).
Tools for the Job
- Socket wrench
- 4" extension (optional)
- 17mm Allen-head socket or 16mm tamperproof triplesquare socket (depending on car)
- Transmission fluid
- Funnel and hose
You can buy the 17mm socket in a set (4mm-17mm) for around $10 from Harbor Freight part #67880 (the 17mm on that set is a 1/2" drive). If you just want the individual socket, the cheapest I've been able to find it is AutoZone for $2.99 part #25285 (made for a 3/8" drive).
Some cars use a 16mm Tamperproof triplesquare socket, which is a bit of a specialty socket, so if your car requires one it will probably end up costing around $10-$20 from eBay.
I'm not sure if there is any rhyme or reason behind what cars use what drain plug but I believe 2003 and up use this plug. The part number on the socket I have is XZN16MH. Searching "xzn 16" indicates it will be $15 on Amazon.
If you don't have a funnel and hose then you can pick up a set of funnels at the dollar store and some cheap rubber hose at Ace Hardware for about 30 cents a foot.
Transmission Fluid ("Oil"). Ultimately the choice is up to you. Our transmissions do contain brass parts and some oils will eat them up. So you want to use an oil that is safe for use on brass, "yellow safe fluid." I personally recommend Pennzoil Synchromesh and have used it on all my dubs without issue. You will need to buy two bottles at about $7 each from any auto parts store. Others have also recommended Redline MT-90, which I have never tried. If you want the OEM oil you can pick it up at the dealership for about $20 a liter.
Standard 5-speed MKIVs will use 2.1 liters; a 6-speed 20th or GLI will require 2.4 liters to fill.
Trans Flush DIY: Steps
- To change out the fluid you will need your car to be level and you will need to get under there, which can be accomplished the easy way or the hard way.
If your car is at stock height or just a little lower then you can get to the drain plug just by parking in front of a curb that drops off or slopes down. Our parking lot slopes down, so I just park on a speed bump and it keeps my car level. If you feel like taking your bumper off you can get to the drain plug and your dogbone mount nice and easy, and change out your bushings as well.
If you want to do it the hard way, you can jack up all four corners of the car and put it on jack stands.
- I like to spray a little Liquid Wrench around the drain plugs to help loosen up the buildup of dirt and grime around the the threads. Then clean the area with an old toothbrush (or your roommate's).
- Unscrew the fill plug first. The last thing you want to do is drain the oil and find out that you can't fill it back up. If you get on the ground and look up under the bumper on the driver's side you will see the fill plug. There is a curved hardline (power steering line?) that on some cars gets in the way and you will need an extension on your socket wrench on most you should be able to get to it just fine. Loosen the plug, pull it out and give it a nice clean.
- The drain plug is located on the driver's side just next to the dogbone/pendulum mount and can be easily reached from the front of the car. Get the plug nice and loose so the fluid is dripping and get your container ready to catch the fluid. They sell low wide oil bowls at AutoZone for $2.99 that look like they would work great for this job, but I'm too cheap to buy one.
- Fully unscrew the plug with your fingers and just let it drop into the container. This stuff stinks so wear gloves or try not to get it all over your hands and arms.
- I'd give it enough time to completely drip out of there, maybe 20-30 minutes or so. Fish the drain plug out of the oil with a stick or something and give it a good clean. Screw it back it with your fingers. The Bentley manual does not specify how much torque you are supposed to tighten the plug with. I tightened it till it was snug, around 22 ft-lb.
- From the top of your engine, run the hose down to the fill hole and stick it in. If you have someone to help you it is best if you can look under the car while someone else pours in your oil. You can pour in one full bottle; you will use about half of the second (at least that's the case with my 32-oz bottles of Synchromesh).
- Once it starts dripping out of the fill hole pull out the hose and screw the plug in with your fingers and tighten with your socket wrench.
Boom! Shananana! You're done! Drive that bad boy around and enjoy your smooth shifts. If you want to be polite pour some cat litter on the huge oil spill you probably just made in the parking lot.
More VW & Audi MK4 DIY's
Here's a list of more DIYs I wrote for Volkswagens and Audis.