Does anyone know any efficiency specs for this filter. 3208 natural oil filter, but that is not what this one is being used for. It's for a friend's Oldsmobile 5.7 diesel, that has an oil filter adapter stud installed (13/16-16 to 1 1/8-16). The original PH11/PH25 oil filters are hard to find, expensive, and the efficiency is not stellar. This engine has a built in bypass valve and the filter is essentially at the level of the bottom of the pan. So the ADBV is not particularly important. And even the large PH11 is fairly small for a 5.7l IDI, with how it soots up the oil. He went to the CAT filter based on ease of purchase (CAT dealer 2 miles away), and that he figured it would be a better filter. The quality is certainly miles above anything available in the PH11 size. It's an Advanced High Efficiency version by the way, the middle of the range.