Answer: Engine oil is responsible for keeping the engine running smoothly. Regular changing of your vehicle’s oil will allow your engine to last much longer. Engine oil reduces the friction among all of the engine’s moving parts. As oil gets old, it doesn’t lubricate the engine’s parts as well and can lead to increased wear and damage. Fresh oil also absorbs and disperses heat much better than old oil does. Oil is also responsible for removing the harmful microscopic wear particles and transferring them to the oil filter. These particles have a tendency to accumulate in old engine oil and won’t allow the oil to absorb any more debris. Dirt and debris will continue to accumulate and can cause more wear to the engine. Dirty oil also moves much slower and makes the engine work much harder to circulate the oil. Eventually, the old oil will stop lubricating the engine and can lead to significant engine damage and possible engine failure.