The inside of this 3.7 liter V-6 Jeep Grand Cherokee motor is covered with what looks like generous portions of chocolate cake frosting. This thick sticky stuff is known as “sludge” and accumulates over time when the engine oil is not regularly changed. In this particular case the camshaft (internal to the engine) actually came loose and had worn a hole through the engine’s valve cover due to camshaft journals (hold the camshaft in place) wearing out well before their time. This is why your car guy tells you to change your motor oil on a regular basis. Most will recommend 3,000 mile changes when the car is driven in town and 5,000 mile changes with regular highway driving. Check your owner’s manual and do what it says!