Oil changes (along with airing your tires & checking your fluid levels) constitute the most basic elements of auto care. Almost everyone (regardless of their understanding of automobiles) realizes that changing your oil is fundamental to keep your vehicle in good working order. How often should you change the oil in your vehicle, though?In order to answer this simple question, it’s good to have a basic understanding of why oil needs to be changed – which in turn helps us with ‘when’ to change it. Essentially, engine oil is replaced for two different reasons: First, the engine gets dirty. Over a period of time, dirt and particles build up in the engine. Second, the oil itself can begin to breakdown. The molecular structure & inherent lubrication qualities are lost for different reasons.
That is it! As simple as it sounds, that is why we change oil.
If you’re looking for more of a technical explanation, read on. Dirt is an abrasive particulate that make its way into the engine through the air intake. Dirt is also the by-product of internal combustion engines on what is known as the ‘exhaust stroke.’ When air is exiting the engine through the exhaust, it reintroduces a small amount of dirt from the exhaust stroke and makes its way back into the engine oil. It gets the oil dirty over a period of time due to the inherent inefficiency of the internal combustion engine design. As long as we have gas and diesel engines we will have to contend with this problem.
Studies clearly show synthetic oil can lengthen oil change intervals because oil doesn’t breakdown as quickly as a standard petroleum-based oil. Synthetic oil does not address the problem with dirt, though. Minute sand and abrasive particles can come thru the air intake, which is why it is also very important to check the air filter. All the air coming into the engine comes thru the air filter. So, if the air filter is dirty, it prematurely corrupts the oil and gets it dirty – regardless of whether you are using synthetic or conventional petroleum-based oil. Remember that dirt is dirt, and it will corrupt the most expensive highly engineered synthetic oil in the world!
We believe that synthetic oil and some of the manufacturer’s recommended service intervals are a bit deceptive. They create a false sense of security as to how long oil changes can be “put off.” For example, there are certain European manufacturers that cover the 1st 40,000 miles of service and only recommend an oil change every 15,000 miles. Because the manufacturer is paying for the service, they tend to stretch out the intervals. They also want to sell you a new car in 4.2 years and do not appear to be terribly concerned about the longevity of your vehicle. It is a real eye opener to see a car with an air filter that hasn’t been changed and hasn’t had the oil changed in 15,000 miles! Usually the oil hasn’t broken down, but you can feel the micro grit between your fingers. When inspecting the air filter, you can see very fine sand and abrasives which are being pulled thru the air intake. These abrasives ultimately travel into your engine oil, which creates engine wear over time.
In addition, geographic location & climate can make a big difference. Here in Reno, Nevada, our climate consists of high desert and low humidity. This tends to dampen the dust & dirt creating dirtier air filters. Quite often, we end up changing air filters before the factory service intervals because dust and dirt shortens it’s life.
Also, some engines tend to sludge due to poor oil passage design and temperature differentials within the engine itself. This is actually less common, but there is some benefit to using synthetic oil in these applications due to the fact that the sludging is caused by oil breakdown. For example, earlier Audi 1.8 turbocharged engines or older Toyota Avalon engines are prone to sludging so synthetic oil & shortening the oil change intervals proves beneficial in these designs.
So, back to our original question: ”When should I change the oil in my car?” At Automotion, we use the following guidelines:
- Conventional oil should be changed (or at least condition checked) about every 3,000 miles
- Synthetic oil should be checked at 5,000 and changed no longer than 7,500 miles
Feel free to stop by Automotion and we’ll be glad to check the oil with you & show you the results.
