Still get mine tested at each change, the latest sample reflected 1.5% fuel (YEA!!!) and the suggestion is to extend it out another 1,000 miles (currently at 5,000 mile changes) Iron and insolubles at 0.3% (soot and heavy crud) running Valvoline Super Blue 5w-40 synthetic and a fleetguard filter.

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07.5 3500 Quad, SRW, 4X4, Laramie, Leathered, Dark Metallic Gray, 6.7, 68RFE, 20K Reese, Ride Rite's, 2 Viair air compressors, Bully steps, Kleinn Locomotive air horns (5 in all), Billet polished locking fuel door, 'A' pillar mount Auto Meter Pryo, PML X-deep trans pan
06 Durango 285 RL 5'er Lifted by KZ