I did an automatic tranny drain and refill on my 08 Corolla and came away quite surprised by how much came out. I ended up letting it drain for around 30 minutes from the drain plug. All the fluid collected into a clean tupperware container that I then drained into a measuring vessel. I got 3.996 quarts from just a drain in an ATF system with only a 7 quart total capacity! Everything I read said that I should only expect 3-3.2 quarts of fluid. I was pleasantly surprised. This was no more difficult than changing the oil. Took 10 minutes of actual work, the rest was letting her drain! By the way, Toyota dealer says the ATF NEVER needs to be serviced.