Every vehicle with a gasoline or diesel engine will need a regularly scheduled oil change. If you're not sure about when the appropriate times for one are, you'll want to keep these four in mind.
1. Every 5,000 to 8,000 Miles
For the vast majority of vehicles that use modern oils, a good ballpark figure is to perform an oil change every 5,000 to 8,000 miles of driving. The old conventional wisdom was every 3,000 miles. However, modern oils are fairly durable, and modern cars put less of a beating on the oil.
Do note that there are exceptions, mostly among classic cars. For example, the original Volkswagen Beetles are notorious for needing oil changes as frequently as every 1,000 miles. This is because they have rear-mounted engines that get terrible air cooling. Learn what the recommendation is for your vehicle. Check with the manufacturer. Also, visit enthusiast websites to learn what the real-world results have been for other drivers.
2. The Oil Is Thin
Regardless of the maintenance schedule for your ride, you should check the oil every few weeks. If it appears to be runny, then it's time for an oil change. If you notice a distinct smell or color, it might also be a sign that there are bad seals or worse problems in the engine.
Adding oil to runny oil is an insufficient solution. Even if the oil level is down, viscosity breakdown tends to be self-perpetuating. Thin oil begets more thin oil so just have a professional change it.
3. Before a Long Trip
Someone planning a trip of more than 1,000 miles should consider an oil change before they set out. This is especially the case if the trip will take you across mountainous terrain that could strain the engine. It's also just as applicable if the trip will take you through a hot region, such as the American Southwest.
4. Every 6 Months
Some folks don't drive their vehicles often or far enough to run into any of the previous issues. That doesn't mean the oil will last forever. As with all fluids, oil separates if it sits for too long.
If you don't drive a lot, there's a risk that the oil can encourage sludge at the bottom of the engine. This can build up and cause a vehicle to struggle. Regular oil change service is necessary for vehicles that don't get much use.