Hello, I recently rebuilt a 4l30e in a '95 525i and I have noticed that when the transmission hasn't warmed up all the way, it locks up the torque converter at around 50-52 but when it warms up it will not lock up the converter unless you are applying significant throttle.  As soon as you return to normal throttle it unlocks again.  Thinking that maybe it might be overserviced (since it doesn't have a dipstick) I have drained about a quart out, at 8oz. increments, and it doesn't seem to have had any effect.