Do a search on Lubro-Moly Diesel Purge. It cleans the fuel system, sometimes making the car run smoother. It's worth it I think. It will trash your fuel filters so I'd purge the system first then change the filters.

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)