Synthetic Vs. Conventional Oil

What's the Difference Between Synthetic & Conventional Oils?

When it comes to the battle between synthetic and conventional oil, many drivers know that synthetic oil is widely considered the winner. Synthetic oil provides exceptional wear protection, engine cleanliness and fuel efficiency, among other advantages. Synthetic oil also lasts longer than conventional, providing additional convenience and savings of money.

But what really makes synthetic oil better than conventional? Let’s explore:

Topics explored will include:

  • What is synthetic oil?
  • How are conventional oils manufactured?
  • How do synthetic base oils differ?
  • Is synthetic oil better?
  • A synthetic oil vs. conventional oil test
  • Benefits of synthetic oil
  • How often should I change synthetic oil?
  • Synthetic vs. conventional oil change interval
  • Can you mix conventional oil with synthetic oil?
  • What is synthetic-blend motor oil?
  • Full synthetic vs. synthetic-blend
  • Types of oil explained: synthetic, blend, conventional & high-mileage
  • Synthetic oil vs. conventional oil: performance in older cars
  • How to make the switch to synthetic motor oil

What is Synthetic Oil?

This is something motorists often wonder. They also wonder what synthetic oil is actually made of. Some people mistakenly think synthetic oil isn’t created from crude-oil sources or other fossil fuels. They assume that if everyone switched to synthetic oil, we would make a big step toward saving the environment—and while that’s an ideal situation, it’s just not true.

Though synthetic and conventional oils differ in performance and the way in which they’re created, they both have roots in crude oil/fossil fuels. 


Motor oil, regardless of whether it’s synthetic or conventional, is created from two essential components: base oils and additives. 

The base oils are mostly responsible for resisting wear, removing heat and minimizing friction. When different chemical additives are included in the formulation, motor oil performance is improved. Additives work to fight chemical breakdown, counterbalance acids, provide additional protection from wear & more—depending upon the intended use and formulation.

To illustrate, consider a quart of oil to be like a glass of lemonade: the water is the base oil and the lemon & sugar are the additives. To circle back to and answer our first question, what is synthetic oil, let’s focus our attention on the base oils.

How are Conventional Oils Manufactured?

The base oils that are used to create conventional motor oil are purified from crude oil. Crude oil refers to a number of different hydrocarbons, and it can be separated into many different products like:

  • Gasoline
  • Jet fuel
  • Diesel fuel
  • Heating oil
  • Convention motor oil base oils

Distillation does have its limits, though. Base oils created by crude oil contain a number of different molecules that are damaging to the lubrication of a vehicle’s engine. Because of this, the performance of the oil can be compromised—and so can your engine. Learn more about the complete history of synthetic oil, including how it was connected to WWII.

How Do Synthetic Base Oils Differ?

Synthetic base oils are not distilled; they are built (also known as chemical synthesis). What does this mean? Crude oil molecules are disassembled to their basic components through the use of chemical reactions. After this has been completed, refiners use uniform molecules (usually ethylene) to build the synthetic base oils from the ground up—the result of which is a pure base oil that does not contain the irregular molecules in conventional base oils distilled from crude oil. This process can be confusing unless you’re a chemist by trade, so let’s look at another analogy:

Consider an old Victorian home that you’ve just purchased. It’s in disrepair, but the bones are full of character. Unfortunately, the foundation has cracks, the plaster needs repairing, the roof leaks and the walls are out of plumb. There are two ways to make necessary repairs: conventionally or synthetically. 


You repair the foundation, patch the plaster, replace damaged shingles and accept the misaligned walls. The renovation isn’t ideal, but it’s cheap and the house will be able to provide you shelter for at least a few years before needing additional upgrades.


Instead of just patching over major issues, you actually take the home apart piece by piece. By removing every shingle, every nail, brick, joist, stud and piece of siding, the home is soon in pieces on the lawn. Now it’s time to rebuild with the best pieces. When you’re done, the synthetically-fixed home is stronger and higher-quality than the conventionally renovated home. 

In the same way, refiners tear down crude oil molecules into essential components and actually physically build the synthetic base oils with the best quality molecules. The end product is best optimized for protecting your engine from wear, stress and excessive heat (this analogy only applies to polyalphaolefin-based synthetic oils…learn more about different synthetic oil groups here).