Well. my experience is that the filters rarely get dirty. Magnets may accumulate some debri but that's it. I do a drain and flush every 15,000-20,000 miles (I know it only gets about 4 quarts) but I use synthetic and this seems to work fine, much less expensive and simple. The Mystique I have does not have a filter by the way or a pan to drop. Pull the plug and the fluid comes out. Do this a few times over a month and you have a full change anyway.
