I have read a bit on here about these and I am currently using one in my wife's Impala. Fram Ultra Guard synthetic. My questions are, I have read where people will leave these on for 2+ oil changes and that got me thinking, why would one leave on the dirty oil filter when doing an oil change, or do you remove it and drain as much of the dirty oil first as you can before you put it back on? Also, with these types of filters supposedly lasting as long as they do, I assume they clean much better than just an average run of the mill filter, but if they do, then will they not clog and/or reduce oil flow/pressure eventually as well? I purchased my Fram just last week and it was based on me thinking this is likely a great filter based on what I read here and on the box. When I purchased it, I had, and still don't, have any intentions of leaving it on for 2+ oil changes even though I'll likely not be anywhere near the mileage this filter is good for. I simply purchased it thinking/knowing this is a good/great filter and I want the best for our new car. On the other end of the spectrum, I have read where someone said why are you spending that kind of money on a great filter if you are changing it out so soon and not reaping it's full benefits? Like I mentioned, my thinking is, why purchase an inferior filter, one that is not going to filter as well, if others are out there, albeit, more expensive, that filter much better? These are just questions and maybe there are reasonable/proven explanations so go easy on me as I just likely/simply don't understand the rational behind these?