Your vehicle's engine has hundreds of moving parts in it.  Theses parts cause friction when they rub against each other and the friction, in turn, causes massive amounts of heat in your engine.  To protect against all of this friction and heat, we introduce lubricating oil into the engine.  The oil has two jobs in the engine.  One is to reduce the amount of friction by putting a layer of oil between the moving parts and the other is to help keep the heat from this friction away from the hottest parts of the engine as it circulates through.

If there were no oil in your engine, the moving parts would create so much heat that they would eventually melt together causing the engine to lock up.  Once those engine parts melt together, there is no getting them apart.  So we can all agree that the oil in your engine is pretty important.

But why change the oil?  Isn't the oil that came with the vehicle good enough?  The answer is no, and here is why...

Over time, oil breaks down.  There are many factors that contribute to the breakdown of the oil in your engine, but heat is the biggest contributing factor.  In addition to the breakdown of the oil itself, there are also additives that are put in engine oil.  These begin to break down and lose their effectiveness over time.  There is also the issue of contamination.  Small bits of dust, dirt and debris get into your engine and make their way into the oil.  All these little bits of "stuff" make the oil much less slippery and much less effective at cushioning the moving parts of the engine.

So, how often should you change the oil?  Most technicians recommend that you get an oil change every 3000 miles for maximum engine protection.  Check your vehicle's owner's manual for the recommendations for your specific vehicle, but be careful.  With the introduction of Synthetic Blend Oil, some manuals recommend an oil change every 7500 miles under certain driving conditions.  Make sure your driving meets those conditions before you decide to risk waiting that long for an oil change.