What micron filter do they use at the pump? What ever it is I am sure they don't replace it enough.

The only thing I can say is ask the store owner. I've found some stores/stations use water block filters or some use just filters. Micron ratings might vary from brand to brand.

http://www.cumminsforum.com/forum/general-diesel-discussion/164414-picking-fuel-stop.html

Next time I stop in Riggins I'll ask the Chevron station on the filter number he's using so I can post it up.