You may have noticed. If you drive a relatively new vehicle, the cost of an oil change has increased. The numbers that identify the oil have decreased. The intervals between oil changes have been, in many cases, extended. Something has changed.
What has changed is the increased use of synthetic motor oil by auto manufacturers. More and more, Original Equipment Manufacturers (or “OEMs” like General Motors, Toyota, Mercedes, and the like) are turning to synthetic oil products in their engines.
Unlike conventional motor oil that is derived and distilled directly from crude oil pumped from deep underground, synthetic oil is made artificially in a lab. It may start its life as a highly-refined base oil stock from crude, or it may be completely artificial. Either way, synthetic oil is composed of molecules that are extremely uniform in size and shape, as opposed to the random form of conventional oil. To this finely-tuned composition, high-quality additives are included to boost its performance in an engine.
Synthetic oil outperforms conventional oil in many conditions, but it also costs more. A lot more. So, why is the automotive industry moving toward synthetic motor oil in their cars, trucks, and SUVs?
The reason can be broken down into three interconnected categories: fuel economy, emission reduction, and powertrain design.
Fuel Economy
It is no secret – rather, it is a hotly debated public and political issue – that improvements in fuel economy is important to conserve natural resources and protect the environment.
In 1975, Congress enacted legislation to reduce energy consumption by increasing the fuel economy of cars and light trucks. The Corporate Average Fuel Economy (CAFE) standard calls for fleet-wide averages to be met by automakers each year. When standards are raised, manufacturers respond by creating more fuel-efficient vehicles.
With a current call for vehicles to meet 54.5 miles per gallon on average by the year 2025 (increased in 2011), automakers have a long way to go to meet the standard. Even with a proposed amendment to roll back the standard to 37mpg, the 2019 result of 25.1 leaves a lot of room for improvement.
Emission Reduction
To reduce the impact of air pollutants on the environment and on human life, the Environmental Protection Agency (EPA) has, for decades, enacted an increasing set of legal standards or requirements that all new vehicles sold in the country must meet to regulate pollutants released into the atmosphere. In April 2020, the EPA (along with the National Highway Traffic Safety Administration) amended the CAFE and greenhouse gas emissions standards for passenger cars and light trucks to cover model years through 2026.
Manufacturers achieve emission reduction by cutting back on the amount of polluting compounds found in exhaust gases (nitrogen oxides, carbon monoxide, and more) with catalytic converters. But emission reduction is also tied to fuel efficiency. The less fuel that is consumed, the less exhaust is produced, including carbon dioxide.
Powertrain Design
To reduce fuel consumption, manufacturers have been making engines that are smaller and lighter weight. Less weight equals less fuel needed to move it along. But smaller also means less power. So, automakers have been working to make engines more powerful as well. One of the ways they accomplish this is to add a turbocharger to increase horsepower.
Smaller, lighter engines are also built to far tighter tolerances. There is less space in between the moving components inside. This can save space, but it also presents a problem with friction and parts coming into contact with one another. Especially since those same engines run hotter than larger ones.
Lower Viscosity
Automakers can do many things to increase fuel economy and reduce emissions, including weight reduction (with smaller engines and lighter materials), aerodynamics, and redesigned tires. Another method is to lower the viscosity of the oil in an engine.
Viscosity is a measure of the thickness of a liquid, its resistance to flow. Oil companies assign a number to designate the viscosity of their products as designated by the American Petroleum Institute (API). The higher the number, the thicker the oil; the lower the number the thinner. You may have heard oil viscosity described with other terms: weight or grade. Each term, weight, grade, and viscosity, refer essentially to the same thing.
Decades ago, straight-weight oil, like SAE 30, was common. The drive to improve fuel economy led to the development of multi-weight oil, like 10W-30, where the first number represents the viscosity when the oil is cold (“W” stands for winter) and the second number reveals the viscosity when the oil is up to operating temperature.
In the eighties and nineties, 10W-30 and 10W-40 were common. Since then, those numbers have been dropping. Today, automakers call for (and oil manufacturers produce) products that are much lower in viscosity. 5W-20 and 5W-30 are most common today, and even lighter-weight oils are used regularly – 0W-20, 0W-16, and even 0W-8.
The Solution and the Problem
Lower-viscosity oil helps to improve fuel economy. It allows for tighter engine tolerances because it is thinner and can seep into smaller spaces where thicker oils cannot. And because it is thinner, it produces less drag on engine components. Moving a thicker fluid requires more energy, so lower viscosity means less energy is consumed, fuel is saved, and emissions are lowered.
But thinner oil has its problems. It has a harder time reducing friction and therefore needs friction modifiers added to the formula to improve its ability. Low-viscosity oil is also more volatile and tends to evaporate easier. And additives need to work harder when included in light-weight oil.
That is where synthetic oil comes into play.
Why Synthetic Oil?
The advantages of synthetic oil overcome the challenges of lower viscosity – and the added cost.
For instance, because of its uniform molecular makeup, the oil can be made to be thinner than oil that has oddly-shaped and random large and small molecules. And because it is made from high-quality base stock, synthetic oil is far more stable across temperature extremes. That makes it a perfect candidate for a smaller, hotter engine.
Synthetic oil is also capable of carrying much higher-quality ingredients – friction modifiers, anti-wear additives, antioxidants, and more.
In addition, synthetics are able to withstand the high heat and high rpms of a turbocharger. They also help to tackle the problem of low-speed preignition (LSPI), a condition that is a byproduct of the high pressure in a small turbo-charged direct injection engine where the air-fuel mixture can ignite all by itself. LSPI is damaging to an engine. The detergents included in synthetic oil help to reduce the likelihood of LSPI.
Synthetic oil costs significantly more than conventional oil, but it is also capable of longer service life. Some synthetics can be relied on for 10K miles or more. Manufacturers have shifted to longer oil change intervals with the use of synthetic oil.
Because synthetic oil can be manufactured to a lower viscosity (some grades of oil are only available in synthetic) and can maintain that viscosity longer without breaking down (leading to longer times between oil changes), and because of its ability to carry higher-quality additives and work in the high heat, high-pressure environment of today’s engines, it is fast becoming the lubricant of choice for auto manufacturers.
Columbia Auto Care & Car Wash | Author: Mike Ales | Copyright
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