How often should you change the oil in your car?

For most modern cars, recommended oil change intervals range between 3,750 and 15,000 miles. Car manufacturers list two oil change intervals in the vehicle's maintenance schedule: the longer interval for "normal" conditions and shorter interval for "severe" conditions. You can find the maintenance schedule in the Owner's Manual or in the Warranty and Maintenance brochure for your car.
Adding enigne oil All moving and rotating parts inside the engine are lubricated by oil. See the engine animation
Severe conditions typically include driving on dusty roads, repeated short trips in low temperatures, extensive idling, towing, etc.

Even if you drive in "normal" driving conditions, keep the oil change intervals somewhere between what is recommended for "normal" and "severe" conditions. The idea is to keep your engine well lubricated, so it will last longer.

Many new cars have an oil life monitoring system that will display a message when the oil change is due. However, in most cars, the oil life monitoring system does not actually measure if the oil is dirty or if the level is low. In addition, to work properly, the system needs to be reset at every oil change.

We recommend changing engine oil every 5,000 miles or 8,000 kilometers for average driving. There are several reasons for that:

There were times when the engine oil was recommended to be changed every 3,000 miles. Gradually, car manufacturers extended the intervals to 5,000, then 8,000 and now, in some cases, to even 15,000 miles. What is going on? Has modern engine technology advanced far enough to eliminate friction? Let's get this myth out of the way, no, that didn't happen. Despite all the hype and fancy-named new technologies, if you take apart any modern engine, you will find the same parts as 50 or 80 years ago: the crankshaft, the connecting rods, the timing chain, the oil pump, and so on.
Modern engines have even more components; for example, variable valve timing and high pressure fuel pumps. All these parts are still lubricated by oil. Any super-advanced modern engine will not last for more than a few minutes without oil. So, what's the secret? Longer oil change intervals became possible mostly thanks to dramatic improvements in engine oil quality. In addition, many modern cars use synthetic oil that lasts longer.

Does that mean that if you use synthetic oil, you can drive without oil changes for 15,000 miles or longer and your engine will not wear? This is another myth.
Low oil level on the dipstick When the oil level is low, the engine wears faster.

Synthetic oil does last longer, but any mechanical device that has moving or rotating parts still wears. What happens to the products of wear? Metal dust and by-products of oxidation mix with engine oil. Does dirty oil have the same lubricating quality as fresh new clean oil? Of course, not.

Another issue is that some amount of oil is normally consumed between oil changes. In modern cars, engines are designed to be fuel efficient and lightweight. Often, better fuel efficiency is achieved at the expense of other considerations. Fierce competition forces car makers to extend oil change intervals in order to show "lower" maintenance costs.

Engine oil level is full, oil is clean The oil level should be close to the "Full" mark, like in this photo.
In some modern engines, this often results in higher oil consumption.

In some cars, if you check the oil level after 5,000 miles, it might be slightly lower. Other cars are known to consume a lot. Try googling 'excessive engine oil consumption' and you will find hundreds of complaints. As the oil level drops, the engine wears faster. Many timing chain failures, for example, are caused by running the engine low on oil. For this reason, it's important to keep an eye on the oil level to make sure you are not running your engine low on oil. In most cars, there is no warning light for low oil level; it must be checked with a dipstick.

Should you change the oil as often as every 3,000 miles? Unless you want to see your mechanic every two months, a 3,000-mile oil change interval is another extreme.
Clean versus sludged up engine Clean versus sludged up engine.
If you check your oil in 3,000 miles after your last oil change, chances are it will still be clean. Unless you race your car on a daily basis, even mineral oil can last longer than 3,000 miles.

Should you change your oil in the recommended time interval if the mileage is very low? Car manufacturers recommend having the oil changes done every 4-6 months or by mileage, whichever comes first. This is based on average driving of 15,000 miles per year. If you only put a couple thousand miles in 4 months, there shouldn't be a big problem if you change your oil in 5 or 6 months instead of 4.
It would be unreasonable for a car manufacturer to deny warranty coverage if you still do your oil changes within the recommended mileage. However, if you want to be sure, consult with your dealer.

Change your oil more often if:
- towing a trailer
- driving in a very hot or very cold climate
- driving mostly short trips
- driving fast, racing
- your car has a turbocharger

Change your oil less often if:
- using premium synthetic oil
- the oil remains clean when the next oil change is due and you keep your oil level topped up
- driving mostly on the highway

One way to tell if your car needs an oil change is to check the oil level and condition on the dipstick. See photos in this post: How to check the oil level and how to read the oil on the dipstick.