I was trying to change the oil in my 99 Ultra CAlssic today and a strange thing happened. When I removed the drain plug and filter only a couple of quarts or less of oil drained out. Im positive it was nearly full when I started and there is still oil on the dipstick indicating that there is still oil in the pan. So why won't the rest of the oil drain out? Is there another drain plug somewhere? I removed the one on the shifter side at the bottom of the trans cover I believe it is. First time this has happened. Thanks.