I had to do a fluid and filter change in my wife's 325xi with an automatic transmission. It takes 5 liters. I looked around for ideas on how to get the red stuff into the little hole including the jug pumps and the various fluid transfer pumps. The problem with all of them is you get about a tablespoon per stroke. -for 5 liters
After thinking about it a little, I bought a 1 1/4 gallon garden sprayer from Harbor Freight for $10. I cut the wand off leaving about 3" and slid about 5" of clear tubing on the stub. Then I dumped the ATF into the sprayer, pumped it up, hung the valve close the the fill hole, locked the valve open (the HF sprayers do this) and smugly watched the fluid flow. I did have to pump a few strokes to add pressure a couple times, but talk about easy. . . It is now officially my "ATF filler"