The Differences Between Synthetic and Conventional Motor Oils

Many vehicle owners have wondered what the differences are between conventional and synthetic motor oils. Mechanics tend to recommend synthetic oil because it is supposed to reduce engine sludge, it does produce fewer emissions, and it’s man-made. The trouble is that it can be up to 10 times the price of conventional oil, so why should you pay extra for it?


What Is It?

Primarily, synthetic oil is just oil, but it is partly man-made. It’s made from base oil, carrier oils, and power additives. The carrier ensures a more even distribution of the included additives.

Both motor oil options are made from refined oil. Most synthetic oils begin with a more refined crude oil, which is pumped from wells deep under the ground, similar to conventional oil. However, some synthetics use compounds that are artificially produced or use the synthetics as the base. The primary difference between traditional and synthetic oil is the level of refinement.

Base oil falls into one of many oil grades, some of which are mineral oils that get extracted from crude while others are fully artificial. All grades have additives included to increase engine performance.

The refinement processes can also be different, which can control purity and molecular size. This, in turn, can reduce engine sludge, lower friction, and boost performance.

Advantages of Synthetics

The advantages of using synthetic oil are plentiful and include a more uniform molecule size that ensures less friction, more additives that can clean your car’s engine, reduced deposits because of the engineering and refinement process, and a cleaner oil that has fewer impurities. Along with such, synthetic oil can also help your vehicle function better in colder weather.

Types of Synthetics

You can find full and synthetic-blend oils, as well. Full synthetic oil is considered the purest form, but there aren’t any global standards to grade the synthetic oil. Every manufacturer has secret processes and ingredients, so the term full synthetic is primarily a marketing term. Most of the US-manufactured synthetic oil comes with a Group III base, which means the full-synthetic oil you purchase from the store isn’t really full synthetic. However, Group III bases are more refined with a mineral oil.

Synthetic-blend oil isn’t as refined as full-synthetic oils. The semi-synthetic oil is blended with traditional/conventional oil. Therefore, you still get the additive advantage and more refinement, but there can still be an inconsistency in molecular size and impurities can still be present. The primary benefit of synthetic blends is based on cost because they are cheaper than a full-synthetic oil and still performs better than conventional oils.

Fewer Oil Changes

Since synthetic oil is better for the engine and doesn’t have as many impurities, you can drive on it longer before requiring an oil change. Conventional oil requires a change every 7,500 miles for most vehicles and usage, along with changing the filter each time. If you use synthetic oil, you only have to change the filter every other oil change. You may also have to change the oil every 10,000 miles or once a year, depending on how often you drive.

Most people do believe that the extra mileage you can go between oil changes makes it worth the higher price for an oil change.


You can’t tell the difference between conventional and synthetic oil just by looking at them, but there are two significant differences. Primarily, they are made differently, but they also run differently, as well. Used oil is thicker and sludgy if it’s conventional, especially if the oil had the same amount of wear and tear. Synthetic oils can also be better for performance and protect your engine by reducing friction.



The Differences Between Synthetic and Conventional Motor Oils

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