Yes, you want the car level, but jacking all four corners up off the ground to accomplish this is doing too much in my opinion. I just jacked up the front passenger wheel, removed the wheel, and when I was ready to drain the tranny, lowered the jack until the car was level again(actually, I had it leaning to the passenger side a bit. This shouldn't be a problem because you don't have to get under the car for anything so I felt comfortable doing it.