Your engine has many moving parts. As these parts shift and rub against each other, the force of friction creates heat. Oil lubricants keep the engine cool by lowering friction and forcing heat away, allowing the internal parts to work together effectively without overheating. Without a good lubricant, parts of the engine rub together and wear each other out. Overtime, heat breaks down the engine's oil making it gummy or watery. When it does, it becomes less effective at lubricating the engine and absorbing heat. Do yourself a favor and check your oil levels, running low on oil is NOT GOOD for your vehicle.