I've probably had my tranny filter kit for 3 years and I finally got the nerve to change the fluid out. Used Mobil 1 synthetic, let it drain overnight, ended up replacing almost 6 quarts. Now that I've got an e28 for an extra car I'm going to tackle all the projects I've been putting off. The tranny service was actually pretty easy, as I've read the procedure so many times. Will probably do again in about 5k as the fluid was a bit dirty.