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What Does Motor Oil Do? - Ultimate Info Guide

Jun 19, 2020 ·

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You’re driving down the road and the oil change reminder comes on in your car. You know this is a signal that it’s time to get your oil changed, but what exactly does this mean? What’s going on under the hood?

Changing the oil in a car is a fairly quick and easy procedure, and it’s essential to keeping your engine clean and running effectively. Over time, regular oil changes will help to remove contaminants that have built up and extend the life of your engine, so it’s a worthwhile investment that shouldn’t be overlooked.

Keep reading to learn everything you need to know about motor oil, including what it does, how often you should change it, the different types of oil and more.

What Does Oil Do in a Car?

According to Pennzoil, the official lubricants provider of UTI and a leading brand in the industry, motor oil was historically a simple mixture of base oil and additives. It was designed to lubricate engine parts, reduce friction, clean, cool and protect the engine.

Today, however, modern synthetic motor oil does much more than just lubricate—it provides wear protection, maintains viscosity over varying temperatures, prevents acid build up, and cleans and protects turbos and modern engine components. 

Engine oil is still made up of base oils and additives—however, the quality has improved dramatically. Base oils make up anywhere from 70-90 percent of the total and are derived from natural gas or crude oil. Additives make up anywhere from 10-30 percent. They include chemicals that act as detergents, friction modifiers, antioxidants, corrosion inhibitors and viscosity index improvers, just to name a few.

Is Motor Oil the Same as Engine Oil?

You might have heard engine oil referred to as motor oil, or vice versa. Both products are the same in the market and simply refer to any substance with base oil that’s laced with additives (anti-wear additives, dispersants and detergents, to name a few).

Oil Viscosity Explained

When talking about motor oil, you’ll often hear the term ‘viscosity’ being used. Essentially, oil viscosity refers to how easily oil pours at a specific temperature. Thinner oils flow easier at lower temperatures and have a lower viscosity, whereas thicker oils have a higher viscosity. 

In cold weather, thin oils reduce friction and help engines to start quicker. In higher temperatures, thick oils maintain oil pressure and film strength, and support heavier loads. 

The viscosity index measures oil’s ability to resist changes in viscosity as temperature changes. Most multi-grade motor oils are formulated with viscosity index improvers, which use polymer additives to help maintain consistent oil viscosity over a wide range of temperatures—protecting engine parts from wear. 

An oil with a higher viscosity index number is able to better retain its viscosity over a broader temperature range. However, these viscosity index improvers will break down over time as the oil ages. Changing your oil regularly will help to prevent this.

What Is Synthetic Oil?

Engine oil has changed significantly over time. When it was first introduced in the 1800s, manufacturers used their own fuel and lubrication techniques, which led to many inconsistencies. The usage of animal fat and vegetable oil evolved into the use of motor oil made from crude; and later came the invention of synthetic oil.

Synthetic motor oil is oil that has gone through a chemically engineered process. When compared to conventional oil molecules, synthetic oil molecules are more uniform in shape and have fewer impurities. Typically, synthetic oil will have higher resistance to oxidation and performs better in extreme high and low temperatures than conventional motor oil made from crude.  

When fully formulated, motor oil is designed to serve a variety of different functions, including:

  • Separating and lubricating moving parts
  • Reducing engine wear
  • Helping to prevent deposits from forming on internal engine components
  • Removing and suspending dirt and contaminants in the oil until these contaminants can be removed at the next oil change
  • Cooling engine parts
  • Maintaining engine fuel efficiency and performance
  • Providing protection across a wide range of temperatures
  • Functioning as hydraulics in variable valve timing
  • Helping protect the emissions system

Is Synthetic Oil Made From Natural Gas Better?

Shell’s Pennzoil brand is known for creating the first synthetic motor oil made from natural gas. In the 1970s, Shell began investigating sources of energy other than crude oil, one of them being natural gas, to make fuel and lubricants.  

The process of turning natural gas into oil is highly complex and has many stages, yet it offers superior benefits when compared to crude oil. Natural gas is very clean, and is free of many of the contaminants found in crude oil. When manufactured through their patented process, the result is a synthetic base oil that is purer and performs better than traditional base oils made from crude.

Thanks to the innovation and forward-thinking culture of Shell, the company was able to develop a full synthetic motor oil made from natural gas. This patented process is known as PurePlus Technology, which designs full synthetic motor oils that provide complete protection without compromise. Watch the video below to learn the details of how this process works:

Other Types of Motor Oil

In addition to synthetic motor oil, there are three other common varieties of motor oil:

  1. Synthetic Blend Motor Oil: This type of oil uses a mixture of synthetic and conventional base oils to provide higher resistance to oxidation and better performance in low temperatures.
  2. High-Mileage Motor Oil: Formulated with unique additives, high-mileage motor oil helps to reduce oil burn-off and prevent oil leaks that can occur in older engines. This oil is designed for newer or late model vehicles with more than 75,000 miles.
  3. Conventional Motor Oil: Lastly, conventional motor oil comes in a variety of viscosity grades and quality levels. It meets the basic API specs recommended by your engine manufacturer, but does not have the added performance found in synthetic motor oils. 

Motor Oil Grades

Today’s motor oils are categorized based on a rating system developed by the Society of Automotive Engineers (SAE), which rates oils by viscosity.

If you’re looking for an oil that has the ability to perform at a wide range of temperatures, you’ll want to opt for a multi-grade viscosity motor oil. An example of an SAE viscosity grade is “0W-20,” where “0” symbolizes the cold temperature viscosity rating, the “W” stands for winter, and the 20 is the operating temperature viscosity rating.

As a general rule of thumb, always look at your vehicle’s owner’s manual to determine the correct motor oil SAE grade for your specific engine.

Another symbol that commonly appears on motor oils is the API “donut.” API stands for the American Petroleum Institute, which offers a stamp of approval to help customers find engine oils that meet the minimum standards set by engine and vehicle manufacturers.  

This symbol has three parts: the top half of the circle, which indicates the API service rating, the center of the circle, which displays the SAE viscosity, and the lower half of the circle, which tells you the oil’s energy-conserving properties.


service symbol


In addition to this, the ILSAC “starburst” can also be found on the motor oil bottle. This symbol appears on engine oils recommended for gasoline engines that have met API and certain fuel economy tests—the requirements of the International Lubricant Standardization and Approval Committee (ILSAC).

ILSAC GF-6 Requirements

The GF-6 is the newest set of lubricant specifications set forth by the ILSAC that are designed to meet the demands of modern engine technology. This next-generation standard for passenger car motor oils calls for an expanded set of harsher testing related to wear protection, oxidation, fuel economy, sludge and protection from Low Speed Pre-Ignition (LSPI).

So why was this development put in place? The ongoing push for greater fuel economy has resulted in engine downsizing that has grown the application of Turbocharged Gasoline Direct Injection (TGDI) engines. These engines require higher protection mentioned previously including protection against LSPI and timing chain wear.

Introduced in 2020, the GF-6 will provide improved protection, better fuel economy and help to reduce emissions for modern engines. Pennzoil motor oils have met these requirements for API SP and ILSAC GF-6, and this can now be seen on the packaging that will be on retailer shelves soon. To learn more about these exciting updates, visit Pennzoil’s website.

The Importance of Changing Oil

Motor oil provides lubrication to the many moving parts of an engine, which helps to avoid damage and keep your engine running smoothly. 

Each time your engine runs, by-products from combustion are collected in your engine oil. If contaminants build up beyond the capacity of the oil, they accumulate and create deposits, sludge and wear in the engine. 

If the oil is not changed regularly, these contaminants can have a negative impact on your vehicle’s overall performance and efficiency. In addition to changing your oil when recommended, it’s important to keep up with regular vehicle maintenance and use a quality motor oil, such as one from Pennzoil.

So how often should you change your oil? Typically, it’s best to change your vehicle’s oil every 3-5,000 miles or your manufacturer’s recommendation. However, this is all dependent on factors such as your vehicle’s age, driving conditions and the type of oil you use. 

Fortunately, many modern-day cars have engine oil indicators and will provide you with a warning signal on your dashboard when your oil is low or when to change the oil. Many dealerships or service centers will also put a sticker on your window with the date you will need your next oil change. 

When in doubt, consult an automotive technician or your vehicle’s manual for recommendations. It’s always better to be on the safe side!

What Happens When Your Car Runs Out of Oil?

If your engine runs out of oil, parts will start to grind together since they don’t have lubrication, and the engine will seize up and eventually stall. This causes damage that is extremely difficult, if not impossible, to reverse. This is why it’s so important to check your oil level regularly and change your oil often!

In addition to your vehicle’s check engine light on your dashboard (if it has one), there are a few other signs to look out for that can indicate it’s time for an oil change.

  • Engine noise: When motor oil is doing its job, it will lubricate the parts in your engine and as a result, keep the engine quiet. However, if your oil level is low or has completely run out, you may start to hear knocking or rumbling sounds. If this occurs, take your car in for an oil change immediately.
  • Smelling oil inside the car: Smelling oil inside your car is a sign that you may have an oil leak. If you ever smell exhaust fumes or gas, your vehicle may be overheating. In either case, you’ll want to take your car in for a maintenance check as soon as possible.
  • Exhaust smoke: It’s normal for your car’s tailpipe to emit translucent vapor, but if you ever notice that this turns to smoke, you may have an oil leak or faulty engine parts.
  • High mileage: As stated previously, most vehicles require an oil change every 3-5,000 miles, or roughly every 3-6 months. If you put a lot of miles on your car one month, you may want to take your car in for an oil change a bit sooner to avoid any issues. This is especially the case if you have an older vehicle. 
  • Dark-colored oil: Clean oil is translucent with an amber hue. Over time, it will turn to a darker color due to collected contaminants and deposits. If you’re checking your oil and notice that it’s turning a dark color, this is a key sign it may be time for an oil change.

Learn More About Car Oil

To learn even more about motor oil, check out the following resources from Pennzoil, America’s most trusted motor oil and the first full synthetic motor oil made from natural gas: 

As UTI’s official lubricants provider, Shell’s Pennzoil and Rotella brands provide all lubricants to UTI’s Automotive and Diesel programs. Shell also provides “life happens” fuel/Visa cards for students and more than $50,000 in annual scholarships! To learn more about how leading brands like Shell work with UTI, check out our Aftermarket Relationships page.

Want to Pursue a Career in the Automotive Industry?

If you’ve always had a passion for the automotive industry, you may want to consider turning this into your career. In UTI’s 51-week Automotive Technology program, you’ll work on everything from simple engine systems to power and performance machines to prepare for a career as an auto technician.1 To learn more, visit our website and request information today.

Wondering what types of careers auto technicians can pursue? Check out our career guide.

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Universal Technical Institute of Illinois, Inc. is approved by the Division of Private Business and Vocational Schools of the Illinois Board of Higher Education.


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