the original TP filter [Franz] was an add-on bypass filter, and worked fine, especally in conjunction w/ the OEM full pressure filter - when I was a tadpole, dad owned a little cab co [3 cars] - his hick mechanic put the Franz filters on the cabs, and they took many many miles without major motor work
googled franz filter and found
this page - the gov uses them?!?!? oil companies use them?!?!?
Bill