Conventional vs. Synthetic Oil: What’s the Difference? 6 Interesting Facts [Explained]

When it comes to maintaining your vehicle, one of the most important decisions you’ll make is choosing the right type of oil.

Conventional oil and synthetic oil are both popular options, but they have distinct differences.

Did you know that according to a nationwide survey of U.S. drivers, 44 percent are unsure or do not believe synthetic oil is better than conventional oil?

In this article, I will compare and contrast conventional and synthetic oil, highlighting the pros and cons of each, so you can make an informed decision on which type of oil is best for your vehicle..

Conventional vs. Synthetic Oil

It may be challenging to fully understand which engine oil type is superior to the other, whether you’re a beginner or an experienced car owner.

So let’s find out the difference between conventional and synthetic oil and answer your questions:

  • Does synthetic oil perform better than conventional oil?
  • Should I switch to synthetic oil instead of conventional oil?

1. What’s the difference between conventional and synthetic oil?

Synthetic oils are made from various chemicals and compounds, making them more stable than conventional oil. Conventional oil is made from refined crude oil, while synthetic oils are made from man-made or synthetic additives and improvers that enhance their performance in cold and hot temperatures.

Here’s a summary of conventional vs. synthetic oil:

PropertiesConventional Engine OilSynthetic Engine Oil
CompositionRefined crude/mineral oil and additivesBase oil, synthetic additives, and modifiers
ProductionSeveral refining processes to remove impuritiesCreated chemically in the laboratory
CostCheaper, between $35 and $75,More expensive, anywhere from $65 to $125
ViscosityHigher viscosityLower viscosity
PerformanceProne to sludge build-up but is better for older carsBetter performance than conventional engine oil

2. What is conventional engine oil?

Conventional engine oil in a nutshell:

-extracted from crude oil
-refined to remove impurities
-cheaper compared to synthetic
-can be blended with synthetic

Conventional motor oil is an engine lubricant directly extracted from crude oil. They are also called mineral or mineral-based engine oil. To remove impurities, crude oil undergoes several refining processes to remove impurities.

Although it’s much cheaper than synthetic, it does the job – to provide lubrication at high temperatures and maintain stability for extended periods. Some manufacturers add their own formula of additives to improve its performance.

Another engine oil is a mixture of semi-synthetic and conventional oil, referred to as semi-synthetic engine oil or synthetic blend. Semi-synthetic oil is better than conventional oil but still inferior to fully synthetic oil.

The most significant advantage of conventional oil is the cost; it is less expensive than synthetic oil, costing up to 10% less. This is because they are made from less refined base oil.

3. What is synthetic oil?

Synthetic oil in a nutshell:

-made of crude oil but refined and processed artificially
-with much more added additives and enhancers
-performs better than conventional oil
-expensive compared to conventional oil

Synthetic oil comes from the same crude oil as conventional oil but is processed artificially with synthetic or man-made additives.

The base oil, additives, and carrier oil ensure an even distribution of the additives used to produce synthetic oil.

All synthetic oils are produced with performance-enhancing additives, but their composition differs with each brand and is considered a trade secret. This is why it is not recommended to mix different engine oil brands.

Scientific control over molecular size and purity is also a result of refinement procedures and constituents. This can improve performance by decreasing sludge buildup and friction.

4. Conventional vs. Synthetic Oil


Synthetic oil has a low viscosity, making them flow faster than conventional oil.

Oil viscosity is an important factor in engine protection. The lower the viscosity of your engine oil, the easier it is for your engine to turn over and start-up.

The higher the viscosity, the harder it is for your engine to turn over and start-up.

Conventional oil has a high viscosity. Conventional oil better protects older engines because they flow more slowly than synthetic oil. Since conventional oil offers better lubrication for aging engines, these vehicle types can start to prefer it to synthetic alternatives.

On the other hand, synthetic oil has a low viscosity, making them flow faster than conventional oil. As a result of having low viscosity, the oil flows more easily inside the engine, reducing pressure on the internal parts and lowering wear and engine damage.

Engine Performance

However, synthetic oil is far superior in terms of overall engine performance. 

Conventional oils indeed offer better lubrication for older engines. Still, they are much more prone to abrasion and chemical deterioration in demanding circumstances, such as colder temperatures.

Proper circulation is hampered by these thicker fluids, which can clog small machinery spaces, resulting in poor engine performance.

However, synthetic oil is far superior in terms of overall engine performance. Due to the lower levels of friction, it protects the engine. Additives aid in the removal of deposits from the engine.

Furthermore, having few or no impurities means it is cleaner, thickens much more gradually, and has few deposits.

Read more:

Advantages of conventional oil

Conventional oil offers better lubrication for aging engines due to its higher viscosity and suitability, as it is the only engine oil available when manufacturing older cars.

Advantages of synthetic oil

Synthetic oil can improve lubrication by adding lubricants that increase the capacity to keep engine parts clean, especially at high temperatures, which reduces wear over time and may make your engine last longer.

It is more stable because it is engineered to keep its viscosity at higher temperatures for longer. It reduces breakdown because it does not need to be changed as frequently as conventional oils.

Since synthetic oil is more durable, your engine is better protected throughout the service interval and doesn’t leave deposits on engine components.

5. When to use conventional over synthetic and vice versa?

For older vehicles, conventional oil is advised as it offers better lubrication for aging engines due to its higher viscosity and suitability.

Although, there is a type of oil specially made for high-mileage cars. High-mileage oil is better for older cars because it contains more detergents than conventional oils, which aid in reducing and getting rid of sludge in the engine.

For modern cars with any engine and mileage, synthetic oil is advised because:

  • of its capability to maintain its viscosity at high temperatures
  • has no detrimental effects on engine performance
  • doesn’t leave any deposits
  • improves engine protection from corrosion and rust

Here’s a very comprehensive comparison by Engineering Explained:

6. Should I switch to synthetic oil?

Choose synthetic oil, especially full synthetic, if you can afford it. 

Technically, the most crucial thing is to ensure that the engine has adequate engine oil to protect its parts. You don’t want to run a car with low or no engine oil.

But if you have to decide which type of oil is better, then it is synthetic oil.

Synthetic oil eliminates the hassles and oversights associated with frequent oil changes and deposits. Use a blend or alternate between full and semi-synthetic oil every other oil change if synthetic oil is too expensive.

Choose synthetic oil, especially full synthetic, if you can afford it. It is the best engine oil available.

Changing the oil in your car will not harm it. Keep a record of the mileage, next oil change date, and oil type.

Consult your owner’s manual or look up the following information: viscosity grade and oil specification. We do not recommend mixing different engine oil viscosities as it can result in an unpredictable impact on your engine’s performance

Mechanics, oil change services, or repair shops can advise you on the best oil for your needs.


The properties that distinguish conventional oil from synthetic oil significantly impact your engine. However, keep in mind that these oils are not necessary.

Although synthetic oil has superior properties, conventional oil will adequately protect your car’s engine. The first and most important thing you can do to keep your vehicle running smoothly is to stick to the service intervals recommended by the manufacturer.

Elevate your car maintenance game by reading our comprehensive guide on engine oil. Learn everything from the basics of oil types, to how to properly maintain and change it. Keep your vehicle running at its best, read our guide now!

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