A while ago I looked up fuel filters for gas pumps. I noticed that there are different micron ratings... I'm not sure if they have a pre-filter then a more efficient filter after that, or if there are just different options? There are 3 different shell stations I will sometimes fill up at around here and all of them have a very slow pump speed with the handle squeezed open. It is the equivalent to about 1/4th open on the bp and 1/2 open at farm fresh station by them. Could the shell stations just use a more efficient filter that inhibits flow? Or is it more likely that they don't change their filters as often and they are clogged? Once at the shell station in town that see's the most volume, a pump was so slow that it took me about 4x longer than normal to fill. It was obvious that the filter was way too old and clogged up with junk on that pump. I wonder if contaminants manage to get by an old filter or if it only slows the flow way down when it gets clogged? Actually the bp station down the road pumps so fast I wonder if he has any filters in there at all... Anyone hear of stations skipping on the filters?