I have run with the single bypass (the slow flow filter) for approximately 35,000 miles, and I am very pleased with it. The mounting point I created is in front of the radiator, so I am getting some oil cooling for free; higher oil capacity is always a good thing; the oil which comes out every 10,000 is of course black (between diesel and deleted) but I saw a bump of 0.1 to 0.3 mpg early on which never went away - suggesting that it truly is filtering every possible bit of crap out. I plumbed it back into the oil fill cap, so I can see the flow coming out evenly and strong and not worry about oil pressure.