Replacing the Manual Transmission Oil

I had a Mk3 Jetta TDI for 445,000 miles. I practiced 100,000-mile manual transmission drains, with the exception of one shorter interval during a differential upgrade. I decided to use the same drain interval on my GTI. Volkswagen does not specify a drain interval for the manual transmission. Regardless, there was no way I was going to just leave the “lifetime oil” in the car. I drained the oil at 101,000 miles and sent it for analysis. The results seemed average, with the exception of copper and iron content being a little high, but still healthy. Given the time and cost of the oil change, I think I will drain every 50,000 miles instead. Here are some notes that I will share about my manual transmission oil change:

First, wear clothes that you don’t mind getting stained. Transmission oil does not drain as smoothly as engine oil. It may be due to the size of the drain; I’m not sure. It can be a splashy mess. Getting the collection pan as close to the drain helps to minimize the splashing. However, you can get only so close before it presents an obstacle to removing the drain plug. In fairness, I did not get drenched in splattered oil. But there were a few tiny drops that made their way to my face and shoulders. I was working on the ground. HAHA!

Next, always, always, always remove the fill plug before the drain plug. If you remove the drain plug, thereby draining the transmission, and then discover that you’re unable to remove the fill plug for some reason (seized, cross-threaded, etc), now you have a car that is not drivable and may actually need to be towed for repairs. If you’re unable to remove the fill plug, at least then you can either drive the car to a shop or devise a plan of attack. On top of that, some online forums members have reported that their Mk7s don’t have a fill plug at all. See the photo above. There’s another way to fill the transmission. I’ll not get into that here, but it’s wise to know how to fill the transmission before draining it. Do you agree?

The manual transmission takes 2.3 liters. So, you’ll need to buy 3 liters to do the job. I’ve seen YouTube videos in which people use funnels and long hoses to fill their transmissions from above the engine bay. That results in a decent mess under the car because, if you’re filling via the fill hole, you add oil until it begins to seep from the fill hole. Using a hose, any oil still in the hose will pour down to the now-overfilled transmission and then dribble onto the floor. The longer the hose, the larger the mess. Sure, it’s been done that way for decades and doesn’t hurt much. But what if I told you there’s a cleaner way? I used a suction device that allowed me to extract oil from the oil bottles and then insert it directly into the fill hole from under the car. After two liters, adding the last bit of oil slowly minimizes dribbles. I used the same device when I replaced my VAQ differential fluid. It was a fantastic tool purchase!

I’ve shared a video on my YouTube channel. Feel free to ask questions.

Freshly Oiled,

Scott

About Scott

I grew up near Houston, TX and served in the U. S. Coast Guard for over 30 years. I have an electronics background and continue to work in the electronics engineering field. I taught myself the basics about automotive systems as well as how to perform some of my own maintenance (cars and bicycles). I became involved with Amateur Radio and computers in 1995. The explosion of technology has made my job and several of my hobbies quite interesting. My hobbies include Volkswagens, bicycling, photography, electronics, amateur radio, web management, and reptiles. Visit my websites to learn more.
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