The following offers some great advice from Car Talk.
Should I do this service when it’s recommended?
In general, yes. Changing your vehicle’s oil is one of the most important things you can do to avoid bringing large bags of money to your mechanic later on…
You may want to consider changing your oil more frequently if:
You drive like a knucklehead: jackrabbit starts, heavy acceleration or high-speed driving
You live where the climate is extremely hot or cold
You often drive on dirt roads
Your engine is old and burns oil
You frequently carry heavy loads (several mothers-in-law or other cargo)…
Why do I have to do this?
Oil undergoes thermal breakdown due to high operating temperature. When this occurs, the oil becomes less effective as a lubricant. And without a good lubricant (read: expensive), parts of the engine rub together and wear each other out…
What happens if I don’t do this?
Your engine won’t last as long as it could. Oil serves many crucial functions, and clean oil performs those functions better than dirty oil. Oil is relatively cheap, and changing your oil every 5,000 miles is a very cheap insurance policy against major repairs down the road.
Is there any maintenance required between intervals?
Yes, you need to check the oil level every few hundred miles. With your car parked on a level surface, remove the oil dipstick, clean it on your brother’s best shirt and then reinsert it. Remove it again, and check the oil level.
Source: Car Talk