Photo courtesy of uchar via

Photo courtesy of uchar via

Preventive maintenance expenses are increasing as more OEMs require the use of more expensive synthetic motor oil for new models, which costs about 60% more than traditional mineral-based motor oils.

This escalating cost will continue as older company vehicles using conventional motor oil are retired from fleet service and replaced by new vehicles requiring synthetic oils. In the 2019-MY, about 70% of all new vehicles were required by the OEM to use either a full or blended synthetic motor oil.

Since synthetic oil has robust additives and fewer impurities, it lasts longer than conventional motor oil or synthetic blends by not breaking down as quickly and retains its viscosity longer. These properties allow OEMs to extend oil drain intervals, offsetting some of the higher transaction costs incurred by end-users. 

There are three key reasons why the transition to synthetic oils is occurring. They are the proliferation of smaller displacement turbocharged engines, escalating CAFE fuel economy requirements, and government regulations to lower tailpipe emissions. 

Pressure to Meet CAFE Mandates

One reason OEMs started to adopt synthetic motor oils was to increase average fuel economy of their overall product portfolio to meet CAFE fuel economy mandates. Over the years, use of conventional motor oil has diminished in favor of synthetic oils.

Prior to 1985, the standard motor oil was 10W-40; however, today it represents just 2% of total sales. The No.1 motor oil today is 5W-30, which accounts for 56% of the light-duty market. Since the 1980s, the viscosity of motor oil has become gradually lower primarily to improve fuel efficiency. This trend is continuing today with the introduction of  even thinner engine oils.

For instance, some new Dodge and Ford models require 5W-20, while newer Toyota and Honda models require 0W-20 and 0W-16 motor oils. (As a cautionary note, always check the vehicle’s owner’s manual to verify the OEM recommended oil grade before changing motor oil.)

Looking to the future, OEMs are investigating the use of even lower viscosity motor oils. For example, Honda is reported to be testing a 0W-8 motor oil. While the fuel efficiency derived from a lower viscosity oil will vary from engine to engine, laboratory tests have shown that changing from a 10W-40 to a 0W-20 oil in an identical engine can results, on average,  in a 3% improvement in fuel economy. 

Proliferation of Turbocharged Engines

Smaller displacement engines tend to run at higher temperatures and oil pressure as OEMs utilize turbocharging technology to boost engine performance. Today, more than 28% of the new vehicles sold are powered by turbocharged engines to supplement the lower horsepower generated by smaller displacement engines.

A turbocharger forces air into an engine to generate extra power when needed. When the turbocharger is not activated, as is the case in most driving, the vehicle is powered by a smaller engine, which uses less fuel.

However, a turbocharged engine tends to run hotter, requiring the use of a synthetic motor oil. Turbocharged cars require the engine oil to lubricate the turbo shaft with a thin layer of oil that is capable of withstanding the severe service of the shaft spinning as much as 20,000 revolutions per minute. As a result, the increased use of turbochargers has prompted the use of a synthetic oil because of its ability to perform and maintain viscosity longevity at higher temperatures.

A synthetic lubricant is able to maintain viscosity during severe operating conditions better than conventional mineral-based lubricants, providing increased protection of engine components. Tests have shown that full synthetic oil functions better in extreme hot and cold temperature and is 47% superior to conventional oil in protecting against metal-to-metal contact. 

Emission Reductions

One way OEMs are looking to reduce tailpipe emissions is by using a lower viscosity motor oil, which produces less friction and decreases fuel consumption. Moving a thicker (more viscous) oil takes more energy. If you reduce viscosity, less energy (fuel) is consumed in the moving parts and in pumping the fluid around the engine. The less fuel burned, the fewer tailpipe emissions that are created. 

Ongoing Trend to Thinner Motor Oils

There are two different types of synthetic oil — synthetic blend oil and full synthetic oil. A synthetic blend oil is a mixture of conventional motor oil and a synthetic base stock. A full synthetic oil uses a synthetic base stock mixed with a variety of additives to boost the performance of the oil.

The trend to lower viscosity oil began decades ago as a way to improve cold-weather lubrication. The Society of Automotive Engineers has a numerical code system for grading motor oils according to their viscosity characteristics. An oil's viscosity corresponds to its thickness.

Using 5W-30 as an example, the 5W represents cold temperature performance. The winter-grade designation of a motor oil is denoted by the letter W, which determines the oil's viscosity at 0 degree Fahrenheit. The second number (30) represents high temperature performance. Both numbers refer to the oil’s fluidity or thickness at different temperatures.

The 5W indicates how quickly the engine will start when cold or in cold weather. The 30 refers to the thickness of the oil when the motor has warmed up. Oil with a lower viscosity provides a quicker flow of oil to cover the engine components, thus minimizing the amount of dry running that occurs when an engine is first started after all of the oil has dripped from the engine into the oil pan. The less viscous the oil, the more smoothly it moves through an engine providing quicker lubrication of moving parts. 

There is a risk, however, to the extension of oil drain intervals, especially if a fleet is not diligent with its PM schedules. Typically, the standard oil change also includes an equipment courtesy check. Extending the oil drain interval to higher miles puts it out-of-synch with courtesy checks for tire wear and brake pad or rotor inspections.

With oil drain intervals as much as 10,000 miles for some models, if you are not vigilant, this could increase the risk of missing early signs of abnormal wear that could be a precursor to more expensive service issues. 

Let me know what you think.

Originally posted on Automotive Fleet

About the author
Mike Antich

Mike Antich

Former Editor and Associate Publisher

Mike Antich covered fleet management and remarketing for more than 20 years and was inducted into the Fleet Hall of Fame in 2010 and the Global Fleet of Hal in 2022. He also won the Industry Icon Award, presented jointly by the IARA and NAAA industry associations.

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