Tips from Used Car Advisor

Car Advisor Tamotsu Todoroki

Hi, this is Tamotsu Todoroki. I am a car advisor of
I write an online column every week to take care of your vehicle. My column is all about something useful and practical for your vehicle. Please have a look once to keep your car in good condition.


How Often Should I Change My Oil? - Vol.187

This age old question has plagued drivers for decades, and it seems that no matter who you ask you will always find differing opinions. Maintaining your engine is nothing to take lightly, and the damages that result from neglect can cost you hundreds and even thousands. How often do you really need to change your oil, and how many of those "service tips" are just opinions?

It is important to first understand why changing your car's oil is necessary. We can relate this topic to washing dishes. Suppose that when you wash your dishes you always use the same water. As time passes the water will become extremely dirty and will no longer serve its purpose. Oil that is allowed to become dirty will no longer be effective, and will actually hinder your vehicles performance.

The Standard
For the longest time the industry standard for oil changes has been every 3,000 miles. Many people still believe this number to be universal, but this is only partly true. Most automobile manufacturers set the standard at 7,500 miles, or once a year for gasoline powered cars and trucks. For diesels and turbo charged engines the standard is every 6 months or 3,000 miles. However, are these universal rules or simply the average numbers across all vehicles?

Around the 1970's the standard oil used in vehicles was 10W-40 oil. This type of oil was primitive in comparison to what we use today, and tended to break down after 3,000 miles. Failure to change the oil at this interval would result in unnecessary engine wear and damage. This is what led to the widespread "3,000-mile" rule.

The Reality
Modern day vehicles no longer use 10W-40 oil, and therefore do not fall under the 3000-mile category. The oil used today is technologically advanced, and much more resilient than the oil used in the past. This means that the 7,500-mile mark is a much more realistic oil-changing interval, but how precise is it?

The reality is that the days of universal oil-changing standards are over. Every present day vehicle that is produced has unique requirements, and cannot be serviced with a one size fits all mentality. For example, if you own a 2012 Volkswagen Jeta the service interval recommended by the manufacturer is every 10,000 miles. Similarly, all 2014 BMW's are set at the 10,000-mile mark. However, if you look across the board you will see that every brand has a slightly varied number, usually in a range from 5,000-15,000.

This is a huge margin for an industry that many assumed to be standardized. The last thing you want is to assume that your car falls under the 10,000-mile mark only to find that you should have serviced the engine 5,000 miles ago. To avoid this simply ask you local dealer what your specifications are.

Severe Use
In addition to all of this, there is another factor that should be considered when estimating your ideal service interval. The mileage amount recommended by your manufacturer is only for ideal conditions. This means that any severe use has not been accounted for. Severe use involves driving in heavy traffic on a regular bases; idling for an extended period of time; driving in weather conditions under 10 degrees or above 90 degrees; and transporting trailers or other heavy loads. Participating in just one of these will qualify you as driving under severe conditions. This means that you should replace your oil on more frequent bases than what is recommended.

What can we conclude from all of this? First, the 3,000 and 7,500 standard intervals are not universal or applicable. Secondly, every car has customized requirements that are specified by the manufacturer. Thirdly, these recommendations are only applicable to those drivers that do not operate their vehicles in severe conditions.