What You Should Know about the Different Types of Motor Oil

What You Should Know about the Different Types of Motor Oil

If you have ever changed your vehicle’s oil, chances are you have been confused about the wide range of different types available. Even if you take your car or truck to a professional, they may ask you what type of oil you want. While the owner’s manual will list the ideal oil for the engine, this assumes moderate temperatures and average driving conditions. In more extreme temperatures or with more strain on the engine, other options may be better. If you are unsure, you can always discuss options with a professional, but having some basic knowledge about the different types of oil available can make the conversation easier. The primary concepts to understand are viscosity and the differences between conventional versus synthetic oil.

What Do the Numbers on a Motor Oil Container Mean?

The numbers on a container of motor oil define the product’s viscosity. The viscosity of a fluid is its resistance to flow. For oil, the viscosity rating comes from the thickness of the fluid at zero degrees Fahrenheit, which is the number that precedes the W on the container label. The W stands for “winter.” The second number is the thickness of the oil at 212 degrees Fahrenheit. Like other fluids, motor oil gets thinner and less viscous as it absorbs heat.

As a general rule, thicker oils provide better lubrication for the moving parts within an engine, so the second number on the label is very important as some oils may become too thin at high temperatures to protect the engine adequately. Oils that are more resistant to thinning at high temperatures have a higher second number. For example, 10W-40 oil is more resistant than 10W-30 oil.

The other side of the viscosity coin is that oil can become excessively thick at low temperatures and have difficulty moving through the engine effectively. With excessively thick oil, the engine will have more difficulty starting because more energy will be required to turn the crankshaft.

For performance in colder weather, you will want a lower number before the W. For example, 5W oils are typically recommended for people in regions with cold winters rather than 10W options. Some synthetic oils actually have a 0W rating. Since engines do better with a high second number in hot climates and a low first number in cold climates, some owners will switch oil types between seasons.

Deciding Between Conventional and Synthetic Motor Oil

The standard oil for most vehicles is the conventional option. Conventional oils come in a wide variety of viscosities and automakers will typically make recommendations about what kind to use. In winter, 5W-20 or 5W-30 is the common recommendation whereas warmer temperatures usually warrant the 10W-30 recommendation. With conventional oil, it is important to change the oil according to the manufacturer’s schedule since it can break down or become dirty, which makes it less effective at lubricating the engine.

You will also find synthetic options at the auto store. Synthetic oil was designed for high-performance and heavy-duty engines. This type of oil includes a number of additives that help maintain flow at both low and high temperatures. Synthetic options go through a wide range of tests before they hit the market. While synthetic options are superior to conventional ones, they are also more expensive and not every engine really needs the additional protection.

Another option is a synthetic blend oil, which combines both synthetic and conventional oils. These blends offer more protection than conventional oil alone and are only slightly more expensive. Often, people with pickup trucks or SUVS opt for blends for the added protection.

More recently, oil companies have introduced high-mileage motor oil. Designed for engines with more than 100,000 miles on them, these options include conditioners that help restore engine seals and reduce leaking. Also, high-mileage oils are usually more viscous, which helps maintain performance in older engines with more miles on them.

Understanding the Different Motor Oil Additives

The other question that often comes up when looking at motor oils involves the additives. Motor oil companies include several additives in their products to protect the engine. For example, motor oil may include detergents, which inhibit the collection of rust, corrosion, and deposits on the engine. Detergents can also help remove some solid deposits. Rust and corrosion inhibitors may be added as well. Dispersants help keep solid particles suspended in the solution, which further protects the engine. Oils can also have anti-wear agents that protect metal surfaces if the lubricating film from the product starts to break down before it is replaced.

Some additives are more about improving performance. For example, friction modifiers help control the rub of engine parts together and can increase fuel economy by reducing the energy needed to move them. Pour-point depressants keep oils flowing at lower temperatures and viscosity-index improvers minimize the oil’s tendency to thin at higher temperatures. Also, many oils have foam inhibitors. The crankshaft can create foam as it moves through the oil pan, which can interfere with the oil’s ability to lubricate, so foam inhibitors are used to reduce the formation of bubbles.

About the Author

A native of the tri-state area, Patrick James Smith has cultivated a lifelong love for travel during trips for work and leisure alike. In planning for his travels, he has become well-versed in the art of travel hacking and utilizing credit card rewards points to book free vacations around the globe.