There are two basic challenges to changing the transmission fluid on the E30 for the DIY’er. The first is to find a 17mm hex (a shallow 17mm at that) to undo the transmission fill and drain plugs. The second challenge is how to actually get new fluid back in because the drain plug is surrounded by the transmission tunnel, some people try to make contraptions that allow them to pump the fluid back in; my method uses good ol’ gravity.   Things you will need for this job: 17mm bolt (the head must be 17mm) A nut that will fit on that bolt Basic small funnel Clear tubing   You will use the bolt and nut as a tool to undo the hex drain bolts. The 17mm head of the bolt will fit in perfectly to do that job. You will put your ratchet/wrench on the nut end. The only hurdle is finding a way to secure the bolt to the nut, because you will be turning the nut counter clockwise (which would make it come off the bolt if not secured). I had a welder handy and just welded the nut and the bolt together, however if you do not have … Continue reading The easy and cheap way to change transmission fluid on an E30