I am thinking of taking out my FS-2500 and installing a BMK-11 and when I do I was thinking of leaving the oil in (Series 30005w-30 with 14,000 miles on it) and just installing the filters EaO & EaBP to see if they really do a better job. With out a oil sample is there a way to just looking at the oil tell if the filters are doing any good and if they were looking good then take a oil sample. I understand what a oil sample does it is just a question.