I run bypass on my 7.3.
Basically, bypass oil filtration is another filter with a much smaller micron rating. Mine filters to 2 microns. Standard oil filters can only filter to about 6 microns, and (according to the mfgs) the real engine wear is caused by the much smaller micron particles of contaminate.
So, you still run the "standard" or OEM filter, and you add another filter body and cartridge which constantly filters out the smaller particles. It keeps the oil much much much more cleaner.
the reason the stock oil filter cannot filter down to that level is that you lose flow. Hence, the "bypass".....some oil bypasses the secondary filter because it is filtering the oil down to the 2 microns.
I average 8500 miles on my dino oil (delo400). I pull a sample at 5000 and send it to blackstone. The tell me how my engine and oil are doing. They tell me (recommend) how much longer to run the oil.
my $.02 is that it is one of the best investments you can make if you want to put alot of miles on your truck......
hope that helps.
