Sun 7th Oct 2018 - 11:45pm General

Even though we are in the business of directing people to oil change coupons via our advertisers, you may want to think about whether or not your oil change is necessary in the first place.

You might have heard in recent years that modern automobile engines generally don’t require oil changes every 3000 miles. Perhaps you have wondered whether or not this is true, wishful thinking, or some combination of the two.

The California Integrated Waste Management Board performed a study not too long ago that found 73 percent of drivers in that state change their oil more often than necessary. It is likely this is very similar in other states nationwide. Obviously, this is a waste of money on the part of the automobile owner. But in the grander scheme of things, it also means we are consuming more oil than we have to – especially in this day and age of insane oil prices.

The data used in this study dates from 2015 and found that in California, there are almost 154 million gallons of oil waste per year. Just under 60% of that oil ends up being recycled or repurposed. One gallon of used oil can affect the taste of a million gallons of water.

It has been a lingering urban legend that motor oil should be changed every 3000 miles. This is in spite of the fact that most automobile makers will recommend oil changes at 5000, 6000, and even 10,000 miles under typical driving scenarios.

Why the change in specifications of automakers? Because motor oil technology has vastly improved. Synthetic oils and engine technology together means that oil stays cleaner longer, without doing any damage to your engine.

Quite simply, the 3000-mile mentality is a lingering holdover from the days when engines used single-grade, non-detergent oils.

GM, BMW, Mercedes, and others have had oil change detection systems included on their autos that notify drivers when it is time to change the oil. GM has a system called the “General Motor Oil LIfe System” which analyzes and monitors a multitude of critical engine systems (engine temp, rpm, average driving speeds, and some other minor conditions) and creates a “rate of engine oil degradation”. The onboard computer then comes up with a calculation of when exactly the oil needs to be changed.

Daimler Chrysler even takes it a step further. Why? Because using mathematical computations by itself is difficult and doesn’t include a number of external variables.

So Daimler uses a special detection circuit that monitors the engine oil directly. Oil doesn’t “wear out”, but instead gets polluted with impurities and other contaminants. When this happens the engine isn’t lubricated correctly and an oil change is needed. Daimler’s system actually detects the “polarity” of the oil. The higher the contaminants, the higher the polarity. So if there are particles in the oil, the polarity is higher, thus prompting the automobile owner to get their oil changed.

The term for this detection is called permittivity. This is measured by applying an AC charge between the interior and exterior of the sensor. The oil flows between these sensors. If the oil transmits well, then the particle rate is high, prompting an oil change.

So we have the mathematical computations, the permittivity test, and now we will talk about a third way of determining the right time for an oil change.

In addition, Daimler measures oil’s viscosity. This is a term you have probably heard before on TV or radio commercials, but probably don’t know much more beyond that. We will be writing more about oil viscosity soon, but suffice it to say, viscosity can be described as “The resistance to flow”.

In motor oil, the viscosity is increased when contaminants are flowing in the oil (as described earlier). Viscosity will also increase when fuel (i.e. gasoline) seeps into the motor oil. Daimler measures viscosity by monitoring the side-to-side motion of oil in the oil sump (reservoir). If the oil moves slowly it has a higher viscosity. The sensor will then calculate and detect high viscosity and signal that an oil change is needed.

Naturally, we do not want to discourage oil changes (or using our oil change coupons site :-) ). But in the interest of saving money – which is likely why you are here in the first place – and wasting oil unnecessarily, it is good to be informed of the 3000-mile oil change myth as well as finding out when you truly do need an oil change.