Your DPF is destroying your truck! The DPF (Diesel Particulate Filter) is an exhaust filter designed to reduce PM (Particle Matter -soot/black smoke) from the environment. This is not green house gas, it is fine dust that settles to the ground. The DPF is a system consisting of a filter, and a complex monitoring and maintenance system that keeps the filter operating correctly. The filter itself is made of a special catalyst which the exhaust from the engine is forced through before leaving the tail pipe. The filter collects PM. As the PM accumulates exhaust pressure builds up behind the filter. This back pressure reduces engine power and engine efficiency. The truck computer monitors the pressure and when it determines the filter is clogged it injects raw diesel fuel into the piston chamber during the exhaust stroke. This un-burnt fuel leaves the piston with the exhaust and ignites in the filter and re-gens (burns), the PM out. This use of fuel for a cleaning process obviously reduces fuel mileage. This re-gen cleaning cycle happens approximately every 100-300 miles and lasts from 15-45 min. This re-gen cleaning cycle only happens at sustained speeds above 45 mph which can cause problems for trucks operating in off road scenarios where low speeds and long idles are the norm such as: airports, oilfields, farming/ranching, and construction. Small amounts of this fuel leaks past the piston and into the engine oil. This diluting of the oil, which reduces the oil's ability to lubricate the engine properly, causes extra wear and reduced engine life. This oil dilution gets worse over time as the un-lubricated piston rings wear and allow more fuel into the oil, which aggravates the problem. Tests show complete lubrication loss in engine oil in as few as 1000 miles. Extreme wear to the point of possible engine failure happens at approximately 100,000 miles even with 5000 mile scheduled oil changes. From Rival Diesel Performance.