I guess I am fortunate that I tow regularly with mine and have reasonable drive time every day. I change my oil at 5K with a sample taken, I can tell when I have extended idle time on the engine, the fuel % is a little high but not over limits. When I just tow, every thing is pretty good on the sample.

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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