1) Why not put Diesel Purge in the new filter?

2) Quite a bit of what is pumped through the injectors while idling goes back to the fuel tank. Next time around it will be diluted. You'll get much better cleaning by cycling Diesel Purge in bottle strength until it's "used up." I say "used up" because you'll stop the process and hook up the fuel tank while the IP and mail filter are full of Diesel Purge.

Sixto
95 S420
87 300SDL