One of the most visceral scenes in the Fast and Furious franchise features Johnny Tran putting the fear of God into his parts supplier, Ted. Tran’s cars don’t have engines days before Race Wars, so he chooses intimidation to convey his boiling anger and get what he needs. “What are you feelin’, Lance?” he asks his pistol-armed associate. “40 weight? 50 weight?” Tran then throws and pins Ted to the ground, grabs an oil pump, and fills Ted’s gullet with the slippery brown stuff.

Lesson No. 1: Oil is not to be consumed by humans. It is to be consumed by engines.

A car simply will not work without its oil. Oil keeps the engine running smoothly, despite the warzone of fiery explosions, metal-on-metal attacks, and crushing pressure occurring within. To understand the importance of oil to your car, as well as the importance of 40 weight vs. 50 weight, Car Bibles will explore what oil is made from and how it works.

What Is Motor Oil and What Does it Do?

Motor oil is a syrupy liquid designed to lubricate a combustion engine’s internal parts. The oil coats the engine’s parts in a thin film to create a slippery protective barrier for optimal efficiency. This keeps the engine running smoothly and helps reduce friction that could cause increases in temperature and wear and tear.

Motor oil also typically features anti-corrosion, cooling, and cleaning properties. Without oil, the engine’s parts would be rubbing metal against metal, the engine would overheat, and it would eventually seize up.

Oil draining out of an engine.

What Is Motor Oil Made Of?

Most modern motor oils are made of two parts: refined base oils and additives. The refined oils used in motor oil are sourced from crude oil. Crude oil is a liquid fossil fuel primarily made of hydrocarbons and is tapped from Earth’s rock layers.

What Are Motor Oil Additives?

Pretty much all manufacturers use additives in their oils. Sometimes the additives are claimed to be detergents, others are claimed to affect the viscosity of the oil, and others are claimed to increase internal engine component protection, among other tasks. The key word when discussing additives is “claim,” as each is somewhat dubious.

An oil filter.

What Are The Different Types of Motor Oil?

As engine technology has progressed over the past 100 years, so too have oil technologies. Today, there are a few different types of motor oil, each of which has specific advantages. We break it down below.


Conventional motor oil, the stuff your mother and grandmother used, is a product distilled and refined from crude oil. Because it is distilled, however, it still contains different molecules that are actually detrimental to motor oil’s purpose. That’s where synthetic comes in.


Unbeknownst to some, synthetic motor oil is still sourced from the refinement of crude oil, but its development, production, design, and purpose are different. Rather than distill the oil down to something like a motor oil product, the molecules are chemically completely broken down, then built back up, or synthesized, into synthetic oil. Because it is built from the ground up, it is built without the performance-damaging molecules that are inherent in conventional oil. The oil-sourced molecules combine with made-made additives to create an extremely pure, sturdy, and efficient product.

Synthetic Blend 

Consider synthetic blend oils, also known as semi-synthetic oils, the hybrids of motor oils. They blend conventional motor oil with synthetic oil.

High Mileage

Oils designed to serve high-mileage vehicles are suggested for use on vehicles with more than 75,000 miles on the clock. Additives aim to protect and condition seals within the engine to help them last longer. Additionally, detergents help clean up the engine. Supposedly.

Natural Gas

Shell made headlines in the automotive world when it announced a new synthetic oil made from natural gas. Shell claims that natural gas is far purer than crude oil to begin with, and thus serves as the base oil for a more refined product.

An oil quart.

How To Read Motor Oil Labels

Every car is designed to operate with a specific type of motor oil. Oils are labeled by the Society of Automotive Engineers (SAE) and are typically formatted as [number, the letter “W,” a dash, and another number]. For example, 5W-30 is a fairly common oil used by many manufacturers for many cars. This code indicates the oil’s range of viscosity, essentially a liquid’s internal friction resistance to movement (physically seen as its thickness or thinness), but not many people know what the letters in the code mean.

If there is a W on your oil’s label, it means you have a multi-grade oil. W stands for Winter, so when the oil thickens up in colder temperatures, the oil’s viscosity is graded a 5. When the oil is at a higher operating temperature, its viscosity is graded a 30. Thus, 5W-30.

Single grade oils also exist and are formatted as SAE30 without any range. This means the oil’s viscosity, also known as the oil’s weight, is 30. These types of oils are typically used in more basic engines like those found in lawn tools, not in car engines.

How Do I Check Engine Oil?

You can easily check the oil level in your engine by locating the dipstick. With the car cooled down, pull the dipstick, wipe it off with a rag, then insert it back into the tube. Pull it back out and inspect the tip. The tip should have indicators of the oil level, whether that’s with words, dots, holes, or hash symbols. Your oil level should fall within the specified range.

How Long Does Motor Oil Last And How Often Should I Change It?

The necessary frequency of oil changes has become one of the most debated topics in automotive maintenance. The old rule of thumb was to change oil every 3,000 miles, but because oil and engine technology has advanced, most consider that rate a waste of time, money, and oil.

Most manufacturers recommend changing the oil roughly every 7,500-10,000 miles, though that ranges between 5,000-15,000 miles. We personally tend to do it sooner than later, even with Mobil 1 synthetic oil that lasts longer, but the best thing to do is follow the manufacturer-recommended schedule.

What Is An Oil Filter And What Does It Do?

As oil snakes its way throughout and around the engine, it passes through an oil filter. Oil filters, which use metal or paper screens or strainers inside a metal shell, are designed to catch unwanted particles floating around in your oil. You should change your oil filter every single time you change your oil.

How To Change Motor Oil

Follow these general steps to complete a quick and easy oil change.

  1. Park your car on a level surface and let it cool down.
  2. Pop the hood and remove the oil cap.
  3. Jack up your car to better access the oil drain plug.
  4. Insert jack stands.
  5. Place an oil drain catch pan beneath the oil drain plug.
  6. Remove the plug and allow the oil to completely drain.
  7. Replace the plug.
  8. Remove the oil filter. Be careful, as it likely has oil inside of it.
  9. Lubricate the seal/gasket on the new oil filter with new oil and tighten it onto the engine.
  10. Use a funnel to add the manufacturer-specified amount of motor oil to the engine.
  11. Put the oil cap back on.
  12. Allow the car to sit for a bit, then check the oil level and add as necessary.
  13. Close the hood, remove the jack stands, and lower the car back to the ground.

That’s it, well done!

Your Questions, Our Answers on Motor Oil

Q: What Kind of Motor Oil Do I Need?

A: That depends on the car! The answer to this question lies within your car’s owner’s manual or service manual. Sometimes, the oil cap on your engine will tell you what it needs, as well.

Q: Is Engine Oil The Same As Motor Oil?

A: Yessirski.

Q: Where Do I Put Engine Oil?

A: Do not put engine oil in the tube your dipstick comes out of. Instead, locate the cap on the top of your engine that is labeled with the type of oil you need.

Q: Can I Just Add Oil To My Car Instead Of Getting An Oil Change?

A: If your oil level is low, and you’ve recently changed your oil, then yes, please do add oil to the appropriate level. However, adding oil to a car does not replace the necessary job of an oil change. Additionally, low engine oil could be a symptom of a bigger problem, so you definitely want to watch your level closely and inspect further as necessary.

Q: How Can I Make Engine Oil?

A: We love the DIY attitude, but you’re out of your mind. Just go to the store and buy it.

Car Bible’s Favorite Motor Oil-Related Products

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