Like any modern diesel vehicle, T6 Rangers need to be taken on regular long drives of a few hundred kms to clean out the DPF filter. The DPF tends to clog up with soot in metro driving or on short trips, but can be blown clear by loading up the Ranger and taking it miles out of town for a good long trip. There have been a raft of problems with Rangers recently brought to light, including engines needing replacement, leaking engine oil from the rear main seal, split intercooler pipes, and even harsh transmission shifts. These aren't unique problems, however, as the Toyota HiLux, Nissan Navara, Mitsubishi Triton and others have all had reported problems of their own. The solution is to buy a Ranger with a comprehensive service history, with low mileage and get it professionally inspected before spending your hard earned. It should last years then.