I just recently got my father a Donaldson oil filter from Amsoil and the Amsoil number is P550428. One thing he noticed different from any other filter he has used was when pre-filling it with oil, one pour filled it to the top, other filters take 3 or 4 pours to fill it up as the filter soaks up the oil and the level drops. Anyone have any experiences like this, or know what the difference is to cause this? The filter is being used on his motor home with a Cummins 5.9 engine, oil used is Amsoil AME 15w40.