Dang!!!! Now I feel like a woose. Here it is deamed as real cold if the temps drop below +10*F. I plugged mine is several times last year just to see what difference it makes at moderate temps. It does make some difference, heater warm up time is definitley faster, engine crank time? no real difference. I have tried 2 and 3 hour plug in times, I don't feel the heater is big enough (High enough heat out put) to heat a cold engine, but it will maintain a warm engine if it left plugged in over night.

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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