An oil change sounds simple, but there's some pretty important things to know about preventing oil sludge.
Oil eventually starts to turn into jelly. Literally – petroleum jelly. Sludge clogs up oil passages and keeps oil from getting to some areas of the engine, causing parts to wear out prematurely. And that means expensive engine repairs.
That's why you need to change the oil and oil filter on schedule – to get the old oil out before it turns to sludge. Your manufacturer will have a recommendation for how many miles you can go between oil changes. They also usually have a number of months between recommended oil changes. That's because the detergents and other additives in the oil break down over time.
Your owner's manual will have a recommendation for time and mileage, but you need to remember that it's based on using the recommended weight of oil. And if your vehicle came from the factory with synthetic oil, the recommended intervals assume you continue to use synthetic.