What's the current thinking on K-Series oil filters? In the world of bikes people get pretty obsessive, stripping them down to compare filtration material, bypass valves etc, and usually conclude that OEM is best. In the case of Rover though, what I'd consider oem (i.e. fitted from new, Unipart I think) has been replaced by a Polish made one which although possibly fine wasn't fitted originally. So..what do people use and why?