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All About Motor Oil

Protection for your engine

The lifeblood of the internal combustion engine, motor oil is vital to the performance of your vehicle. With many moving parts, your engine builds up friction and heat as all these parts rub together. Motor oil not only lubricates the engine, it also absorbs heat to help it run smoothly and efficiently.

From the different types of oil to its various grades, read on to learn all about motor oil. The knowledge you gain can help you make informed decisions about the care and maintenance of your vehicle.

Types of motor oil


Conventional oil – The industry standard for many decades, conventional oil is made from crude oil that has been pulled from the ground. The oil is refined and combined with additives that help with engine protection, viscosity and heat breakdown. The least expensive kind of motor oil, you can expect to change it between 3,000 and 5,000 miles.


Synthetic oil – Made up of chemical compounds, synthetic oil is created in the lab. High-performance additives are blended in to enhance friction-reducing properties. Synthetic oil is effective at reducing friction, handling extreme temperatures and flowing well through the engine. Designed to be changed between 10,000 and 20,000 miles, synthetic oil can last up to three times longer than conventional oil. While it is typically the most expensive oil, you could end up saving money thanks to fewer oil changes.


Synthetic blend oil - A hybrid of conventional oil and synthetic oil, synthetic blend oil gives you many of the benefits of full synthetic oil without the higher cost. The chemical additives help resist oxidation and improve performance in extreme temperatures. On average, you can expect to go about 7,500 miles between oil changes.


High mileage oil – Designed for vehicles with more than 75,000 miles on the odometer, high mileage oil has additives and seal conditioners that can help reduce leaks and extend engine life. High mileage oil can also protect against deposit buildups, sludge and friction. Manufactured in different formulations including conventional, synthetic and synthetic blend, be sure to read the label to know what kind of high mileage oil you are getting.

Grades of motor oil

The grade is the combination of numbers and letters you see on every bottle of motor oil. There are many different grades of motor oil available, each designed for certain operating conditions. Some common grades that you might be familiar with include 5W-40, 5W-30, 10W-30, 10W-40, 15W-40 and 20W-50. There are also multi-grade oils that are for use in vintage or antique engines.


Cracking the code

To fully understand the different grades of motor oil, you need to know what the numbers and letters mean. Let’s look at 10W-40 oil.

For starters, you may be surprised to learn that the W stands for winter and not weight as many people believe. This first number – 10W – refers to the cold weather viscosity (flow rate) of the oil. The lower the number, the less viscous the oil is at cold temperatures (0°F). For example, 5W motor oil flows better in cold temperatures than 15W oil. Oil tends to thicken at low temperatures, so if you live in a cold region, your engine might benefit from a 5W viscosity oil.

The second number (40) rates how thick the oil is under normal operating temperatures (212°F). The higher the number, the thicker the oil is and the better it resists thinning at high temperatures. Grades like 15W-40 and 20W-50 were developed for use in warm climates.


What type/grade of oil should I use?

Consulting your owner’s manual is the best place to look when deciding what type of motor oil to use in your engine. You’ll find manufacturer recommendations on the type and grade of motor oil you should use.

If you are contemplating switching to a different type or grade of motor oil, talk it over with your trusted mechanic. They’ll be able to help you weigh the pros and cons and come to a decision that is best for your vehicle and its engine.


Learn more about vehicle maintenance products, find your car part, or find where to buy your auto part today.

The content contained in this article is for entertainment and informational purposes only and should not be used in lieu of seeking professional advice from a certified technician or mechanic. We encourage you to consult with a certified technician or mechanic if you have specific questions or concerns relating to any of the topics covered herein. Under no circumstances will we be liable for any loss or damage caused by your reliance on any content.