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Can you mix synthetic and conventional oil?

If you’re wondering, Can you mix synthetic and conventional oil, the answer is Yes, mixing synthetic oil and conventional oil is safe. But mixing conventional oils with synthetic oil reduces the high potency of synthetic oils and deprives your engine of synthetic oils’ benefits. 

Although mixing synthetic and conventional oils in the engine does not cause any fatal damage, it is best to mix these oils only when your engine oil is running out and you just need to reach the next oil change stop. And, of course, when you get to the oil stoppage, changing this oil mixture is a must. 

This article will share more about synthetic and conventional oils and let you know more about mixing synthetic oil and conventional oil.

Can you mix synthetic and conventional oil

 Synthetic oil 

It’s an artificial chemical compound made with high potency, suitable for working at extreme temperatures. That is why it is known as synthetic oil

It was created in 1929 as an alternative to powered crude petroleum oil-based engines. People used it in everything from high–powered vehicles to jet engines. When the German army faced an oil crisis during World War II, they relied on this synthetic oil. Similarly, this oil is being used without hesitation in aircraft engines and high-performing vehicles in the present era.

Conventional Oil

Conventional oils are hydrocarbons that have been emitted or produced from the decay of living organisms and dead plants for thousands of years. The intense pressure and heat on the ground cause a terrible reaction, which affects the fossil to turn into crude oil. This refining crude oil produced from the ground makes mineral-based products such as conventional oils. This oil is unrefined for its medicinal properties.

Moreover, this oil or lubricant was used in the late 1800s and was first tried by John Ellis. It was then used as a lube in steam engines. However, this oil is liquid under pressure conditions and at atmospheric temperature, and therefore it can flow without additional stimulation.

 Synthetic oil vs. conventional oil

The major difference between synthetic and conventional oils is their origin. Conventional oil uses crude oil as its base, and synthetic oils are engineered in labs with different ingredients. 

Conventional petroleum oil or motor oil is thinner at high temperatures and thicker at lower temperatures, and manufacturers use additives to change this variation. At high temperatures, the oil condenses a lot, and at low temperatures, it condenses to form mud, in which the chemical additives used are lost or evaporated over time.

As for synthetic oils, these oils are designed to be compatible with any other multi-grade oil. Synthetic oils don’t change or decrease their viscosity without additives and maybe slightly thicker than contaminants.

Which oil should you use-Synthetic or Conventional?

Newer petrol engines are more complex than ever before. Therefore, engine manufacturers recommend using synthetic oils in the running parts of their engines. Synthetic oil is more effective for tolerance and prevents high compression because of its higher chemical stability than other oils. 

Also, synthetic oil is suitable because it evaporates less. It condenses less even in cold weather and does not allow mud to form in the engine like conventional oil. Moreover, the life cycle of synthetic oil is much longer than that of conventional oil. Usually, conventional oil needs to be changed after 3000 to 5000 miles, whereas you need to change synthetic oil after 7500 to 15000 miles.

However, if your engine is not suitable for synthetic oil, it is better not to use it forcibly. Usually, synthetic oil is unsuitable for older engines because of its thin chemical composition. 

Therefore, before using conventional oil or synthetic oils, you must follow the engine manufacturer’s instructions to know which oil offers the best performance to your engine.

How is synthetic oil better than conventional oil?

Synthetic oils are made through a slightly more complex process. In this process, all the impurities available in the oil are being removed, and then the molecules of the oil are shaped to meet the demand of modern engines. Therefore, if you use this oil in your modern engines, you will get an excellent result. 

Furthermore, synthetic oils increase the engine’s efficiency compared to conventional oils and provide a higher level of protection. Synthetic oil supplies different pressures to the various engine parts and protects the engine for up to 250000 miles.

Benefits of synthetic oils 

Prevent Friction: One of the reasons why an engine’s performance decreases is friction. Engine parts are constantly causing friction, which leads the engine to a performance problem. Synthetic oils provide high-quality protection to the engine. It has fewer impurities and prevents deposits and sludge formation.

Suitable for low and High temperatures: Synthetic oils have a much higher stabilizing and viscosity capacity. They are more convenient than conventional oils at both lower and higher temperatures. This oil is specially designed to flow faster in cold temperatures and withstand high temperatures, allowing your engine to run smoothly.

Suitable for Turbocharge Engines: Conventional and synthetic blend oils break down very quickly. It leads your turbocharged engine to fail. Whereas fully synthetic oil provides maximum power and performance to your turbocharged engines. Synthetic oils flow fast to the engine parts, making the engine effectively oily.

Why should I avoid mixing conventional oil with synthetic oil?

Synthetic lubricants are high in quality than conventional oil. They are usually made through a high–quality process that removes various impurities from the oil and keeps the high-quality additives. That is why it is best to avoid combining synthetic oils with conventional oils. Moreover, in the case of an engine, mixing oil is a little bit risky.

What happens when you mix conventional oil with synthetic oil?

It is a common question whether you can mix these two oils or not. The answer is Yes, you can mix them. But if you do it regularly, it will harm your engine. So, let’s find out why you can’t always mix 2- types of oil.

Oil is usually passed through the engine. It lubricates the engine’s moving parts to prevent overheating the components or reducing friction. Conventional engine oil is derived from crude oil; this oil works best in the design of ordinary engines. 

On the other hand, synthetic oils are chemically engineered. They have high resistance to oxidation and rust even in cold weather. These oils flow without any problems. Therefore, they are much more effective. 

However, mixing these 2-types of oils reduces synthetic oil’s potentiality and doesn’t add any qualitative and functional value to the engine. Under high turbo conditions, this mixture breaks down faster and deposits on turbocharger components, causing engines to fail.

How often do you change the oil?

3- variables determine the timing of your oil change: engine model, engine design, and the year it was built. Vehicles built before 1990, such as trucks and SUVs, need to change the oil every 3- months or every 3000 miles. 

But now car engines are much more advanced, and the oil chemistry is longer than before. So modern cars need to get changed less oil than in the past. If you use synthetic oil in the car, it will be able to prolong the time of oil change. 

The 2002 chevy Silverado car uses synthetic oil to keep its engine running smoothly. The use of synthetic oil allows the vehicle to change the oil after traveling approximately 7500 to 10000 miles.


You can sometimes mix synthetic or conventional oils in car engines, but it’s best to avoid it. Even if you combine these 2- oils, changing the engine oil is necessary. Synthetic oils are much better and more beneficial in terms of quality. Mixing it with conventional oil will not boost the performance of the engine. But it may increase the degradation of oil and cost.

So, after reading this article, we hope now you have a clear idea about whether can you mix synthetic and conventional oil or not. Also, we recommend you always check specified by the owner’s manual for that particular truck or vehicle before changing the oil.

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