Yes the oil is clean, the jeep runs fine no overheating; however, it has a small misfire when I stop at a light or when in idle under load but it does not stall. The other sign is that I see more water than normal dripping from the exhaust, no smoke though. My coolant level in the reservoir has lowered a little. The water pump and thermostat were just replaced due to the water pump failing. But that is about it. So, my next step is buying one of those test kits to identify CO2 in the system, dont know if they are any good or not. I really dont want to tear down the engine if I really dont need to.....