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Is Motor Oil the Same As Engine Oil?

Is Motor Oil the Same As Engine Oil?

When discussing vehicle maintenance you may hear terms thrown around like motor oil and engine oil and wonder if they’re the same thing!

Although the terms motor oil and engine oil are often used interchangeably, they actually refer to two different types of lubricating oils. Motor oils lubricate your engine’s moving parts while engine oils help keep engines clean and free of corrosion.

Keep reading to learn more about motor and engine oil!

Is Engine And Motor Oil The Same Thing?

Many car owners think that motor oil and engine oil are the same things. But, they’re not!

Motor oil and engine oil often get interchanged to refer to base oil substances integrated with additives. Additives can be dispersants, detergents, pour point depressants, anti-wear additives, foam inhibitors, and viscosity improvers. 

Motor oil is typically more viscous than engine oil because it has to withstand higher temperatures. It also contains additives that resist metal wear and rusting inside the engine.

In the current market, engine oil and motor oil are very similar products.

Engine oil has multiple functions:

  • Protection from corrosion and rust
  • Lubricating engine components, and 
  • Preventing sludge and deposit build-up

It also enhances sealing, maintains cool temperatures in the engine, and eliminates contaminants while neutralizing acidity to avoid degradation.

Engine oils have two components, additives, and base oil. The base oil can be synthetic, semi-synthetic, or mineral. Most diesel engines use engine oil with a mineral base. 

The additives improve the oil’s physical and chemical properties to enhance performance. They make up about 25% of the oil, depending on the oil’s application and quality.

Synthetic and semi-synthetic are popular in petrol engines with service intervals spread far apart or operate at higher conditions. These oils are more refined and therefore more expensive.

Given the similarities between engine and motor oil, you may also be wondering how to figure out which is the right one to use!

The answer is actually pretty simple – just look at your owner’s manual or ask a mechanic 😉

Can I Put Motor Oil in My Engine?

The safest answer here is to simply check your vehicle’s owner’s manual, or double-check with a local mechanic.

The car manual has a list of the approved oil weight and the standard oil format. The format number shows the appropriate oil viscosity. 

It’s best to stick to the type of oil recommended by the car’s manufacturer to ensure optimal performance and avoid mechanical issues down the road.

Different Types of Engine/Motor Oil

Now that we’ve established that engine and motor oil are the same, let’s take a look at the different types out there.

Mineral-Based Oil

Mineral-based or conventional oils contain additives such as Zinc dialkyl dithiophosphate (ZDDP), which is responsible for inhibiting corrosion and wear. Additional components include Phosphorus (antiwear, anti-foaming agent), Sulfur (antiwear, friction modifier, anti-foaming agent), and Nitrogen (antioxidant).

Mineral-based oils are available in two grades: Petroleum Engine Oil (SAE 10W/30; 5W/20; etc.) and its alternative Synthetic Engine Oil (SAE 0W/40).

These oils contain high levels of alkane and aromatic hydrocarbons, which make them very dense and quickly get solidified at low temperatures. They do not form any sediments but solidify over time, resulting in the engine wearing out prematurely.

This oil is still used in some inexpensive cars or when a car manufacturer does not provide an option for semi-synthetic or synthetic motor oil.

When it comes to oxidation and lubrication, this type of oil is inferior, making it one of the significant disadvantages. They are also replaced more frequently compared to other oils. The last con is the oil can’t withstand high temperatures.

Synthetic Oil / Semi-Synthetic Oil

In contrast to petroleum oil, Synthetic oils are much more refined and processed in a unique distillation process. They are manufactured using a base fluid made from a blend of polyalphaolefins (PAO) which contain an average alkane molecular chain length of 20 carbons.

The advantages include improved oxidation resistance, thermal stability, and resistance to high-temperature corrosion. The main con is it’s relatively more expensive.

The base fluid for synthetic oil is synthesized from various raw materials such as natural gas, coal, petroleum, or bio-based raw materials according to ASTM D 4485 category definitions.

In response to market preferences over the past few decades, environmental considerations have increasingly led fuel manufacturers to offer specifications for their products since 2008.

This has enabled the development of a wide range of semi-synthetic products that provide benefits for both fuel economy and engine protection. Thus, it can be seen that this oil is one of the best alternatives to mineral-based oils.

Full Synthetic Engine Oil

Full synthetic oils are mainly derived from high-purity synthetic base fluid, which is synthesized at very high pressure and temperature under strictly controlled conditions. The fully synthetic oil simply means that it does not contain any mineral components.

The advantage of this oil over other types is that there are no dry starts because the instantaneous lubrication ensures protection against wear for instant starting after a long idle period. It also provides superior protection against oxidation compared to other types of engine oils.

However, these oils are expensive but can last longer due to their excellent resistance to heat and oxidation, thus giving the added benefit of payback through an extended oil change interval (i.e., up to 15,000 miles). Another major con is they do not work very well in cold temperatures until they are fully warmed up.

Petroleum-Based Synthetic Oil

A blend refers to the combination of both synthetic and mineral oil, which contains 25%-30% synthetic base fluid blended with 70-75% petroleum-based mineral oil. Their very clear color can easily identify them compared with other types of oils.

The advantage of using this type of oil is that it provides better protection than conventional or semi-synthetic oils but still at a lower price than fully synthetic oils. It also works well in high-temperature conditions but is not as effective as full synthetic engine oil against oxidation.

One disadvantage is that it does not protect your car as well as 100% synthetics do in colder climates. One other con is that petroleum-based oils are not as common as the others.

Frequently Asked Questions (FAQs)

What happens if you add synthetic oil to mineral engine oil?

There’s no harm in mixing the two. The only downside is that you’ll miss out on the benefits of synthetic oil, which is more expensive than mineral oil.

What if you mix different oil brands?

It’s not advisable to mix engine oil brands due to the varying viscosity. However, it has no significant effect on your engine.

How often should you change your oil?

The recommendation for an oil change is after every 3,000 to 5,000 miles, or according to the manufacturer’s specifications. However, this also depends on other factors such as; driving conditions, type of oil you’re using, and age of the car.

Motor oil is the same as engine oil; different manufacturers choose to label the products interchangeably.

When selecting the engine oil brand to use, check for the starburst symbol. It confirms that the American Petroleum Institute (API) has tested and approved the oil.

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Zach Reed

Hi, I'm the founder of! Having owned a wide variety of vehicles in my life, I was astounded at how hard it can be to find answers to common automotive questions. Rather than sit idly, I decided to create this website to help others!