Dump it. If you are asking it's probably time, go with your instinct. As an owner of multiple quick lube locations, the 6.0 has the most complaints from our customers. My 08 6.4 has been great, only a leaky radiator hose in 67,000 miles and that was covered under the 100,000 mile engine warranty. Also 3,500 miles in baja with who knows waht kind of fuel being put in. I do change my oil, all synthetics, and fuel filters before and after going and change the gear box and trans fluids way more than Ford recommends. One advantage to getting parts at cost and having free labor.