Hey guys I'm going to school for diesel mechanics right now and last week we had a rep from Cat come in and do a 2 day class with us and we got on the topic of which oil filters were the best and he told us he went to come kind of trade show or whatever a few months ago and they had all kinds of oil filters ranging from the cheapo to the most expensive filters on the market all lined up next to each other and they were all cross-sectioned. He asked us which one we thought looked the best and most replied Fram K&N or Mobile1 and he said believe it or not the best internally constructed oil filter is the Purilator PureOne filter and the worst was the Fram......