So I'm planning on a little trans service.. I'm getting some mixed info, specifically on changing the filter - does this need to be done? Given I have to drop the pan to drain the fluid, should I just get the filter done while I'm at it? Also, do the ST162s have a magnet on the pan to catch lose flakes? If not, would there be harm in putting one in? I'm getting some mixed info on the capacity too. To refill after I drain it, how much would be needed (given some remains)?