How often should you change the oil in your car?

Car makers recommend different oil change intervals for different cars; typically between 5,000 and 7,500 miles or between 4 and 6 months, whichever comes first for normal driving conditions. Recommended oil change intervals for severe driving conditions are usually shorter: 3,500-5,000 miles or 3-4 months.

Clean versus sludged up engine
Changing oil regularly helps keep the engine clean inside and prolong its life.

Severe conditions include driving on dusty roads, repeated short trips in low temperatures, extensive idling, towing, etc. We recommend keeping the oil change intervals somewhere between what is recommended for “normal” and “severe” conditions:

Change your oil more often if your car has a turbocharger or if you notice that the engine consumes oil or if you like spirited driving or use your vehicle for towing. Change your oil less often if you use premium synthetic oil, keep the oil level topped up, drive mostly on the highway and your oil remains clean when the next oil change is due.

Why does engine oil need to be changed? The engine has many moving and rotating parts. Modern cars have smaller fuel-efficient engines that run hotter and have more complex components such as variable valve timing, valve lift, turbochargers and high pressure fuel pumps.

4-cylinder engine inside

All of these parts are not only lubricated and cooled by oil, but require proper oil pressure to work. Any modern engine will not last for more than a few minutes without oil. An average 4-cylinder engine is filled with 4.2-4.5 quarts (4.0-4.2 liters) of oil; larger engines take in more. An oil pump circulates the oil through the oil filter and the engine lubrication system.

As you drive, some amount of oil is normally consumed and the remaining oil deteriorates and becomes contaminated with products of wear. For this reason, the engine oil and oil filter need to be changed in regular mileage or time intervals. Many engine problems are caused by lack of oil changes.

What is an oil life monitoring system? Many modern cars have an oil life monitoring system that will display a message when the oil change is due.

Low oil level on the dipstick

However, in most cars, the oil life monitoring system does not measure if the oil is dirty or if the oil level is low. It only monitors the mileage and time since your last oil change, taking into account your driving style. This means that the oil life monitor needs to be reset at every oil change to work properly. The reality is that we have seen many cases where the oil life monitor was not reset for one reason or another causing confusion and unnecessary service visits.

Considering that many modern engines are known to consume oil, it’s also important to check the oil level regularly. 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. In most cars, there is no warning light for low oil level; it must be checked manually, with a dipstick.

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