I just changed my oil and the oil looked disgusting after the 3750 mile change interval recommended by Kia. It looked really dirty, much dirtier than the previous two changes. I also noticed that the coolant looked low. Are the 3.5L Lambda II engines bad on head gaskets? I only have 45,000 miles and will be beyond peeved if it needs a head gasket replacement this early in its lifespan.