What happens if you use regular oil instead of synthetic oil?

regular oil synthetic

There's a belief that after using synthetic oil, you can never go back to regular oil as synthetic oil is better than traditional oil. Is there a basis for this claim?

This guide will help answer the question, "Can you use regular oil after synthetic" and expose the truths to synthetic oil vs regular oil. Your car should always be in the best condition possible, and learning all about the right kind of oil to use will enhance the value of your vehicle and will keep you and your family safe on the road.


Can you use regular oil after synthetic oil?

A simple answer would be YES.

Yes, you can use regular oil after using synthetic oil with no problems at all. Both are oils and have the same application. According to Mobil Oils, one of the leading manufacturers of engine motor oils, synthetic motor oils provide improved protection compared to conventional oils, but there's no reason to worry if you switch to full synthetic and regular oil. This won't damage your engine. But the engine oil giant also stated that this might also depend on the current condition of the engine and the overall quality of the traditional oil to be used.

Can you mix synthetic oil with regular oil?

Another easy answer is YES. Yes, you can mix regular oil with synthetic oils because these oils have the same function, and that is to protect your engine. However, there are some things to consider:

  • Synthetic oils were developed by experts to extend the life of your engine; therefore, you are reducing the function of the synthetic oil by mixing it with regular oil.
  • Additives in synthetic oil clean the engine of any deposits. Mixing regular oil with synthetic oil is like adding impurities instead of removing them.
  • The goal of synthetic oils is to improve the performance of a car's engine and guarantees longer gaps between changes. Therefore, mixing regular oil with synthetic oils reduces the oil's main purpose.

Comparing synthetic oil and regular oil

Synthetic oil and regular oils are not as different as you may think. Both are made with the same materials called lubricants that can enhance engine performance. But the main difference is the additives that are found in synthetic oils.

Also, synthetic oils have fewer impurities, and thus there is less friction inside the engine. And when there's less friction, engines work better and will also keep better.  According to a test for mileage, synthetic oils can give up to 2% better mileage, which translates to a gallon of fuel for every year.

Still, another reason why many car owners prefer synthetic oils is that it's about 4 times more effective compared to regular oil. Synthetic engine oils can give you 15,000 miles, while the top quality conventional oil can give you 5,000 miles only.

Consider that you're reducing the performance of synthetic oils when you mix these with regular oils. Also, you are more likely to change oils more often than using only pure synthetic oils.

How to mix synthetic oil with regular oil?

The following content is just to show you how mixing oils are done as we recommend using synthetic oils only for proper engine mileage. Mix regular oils with synthetic only as of the last result if synthetic oils are not available in your area.

  1. Be sure that your car is parked on safe and level ground before you start.
  2. Power off the engine.
  3. Check engine oil.
  4. Add regular oil to synthetic oil.
    If you're low on synthetic oil and there are no synthetic oil products nearby, you may use regular oil.
  5. Replace the engine oil cap.

When it comes to replacing regular oil with conventional oil, it's recommended that you drain all regular oil and replace it with synthetic oils. Doing so will help remove all impurities present in conventional oil before adding safe, pure, and dependable synthetic engine oil. 

But when you're switching from synthetic to conventional oil, there's no need to drain synthetic oils from the engine as you are replacing clean oil with more impurities. All you need to do is to check the level engine oil levels first and simply add the regular oil to the engine oil cap.

Mixing oils won't damage your car but will greatly affect the efficiency of your vehicle and the cleanliness of your car's engine.

As always, if you're unsure as to how your car engine oil is replaced, ask a professional car repair expert to help you out.

Interested on the oil catch can buyer’s guide? Click here

You put the wrong oil in your car?

Over the years, car owners have seen the benefit of synthetic oils and considered it a better option than regular oils. Therefore, you must expect the following when you use poor-quality, wrong oil in your car:

Expect poor engine performance, especially in extreme temperatures.

When conventional oils are exposed to extreme cold, these lose their lubrication quality. When exposed to very hot environments, regular oils can breakdown quicker than synthetic oils.

The post talked about 5W30 and 10w30 temperature range

Expect a dirty, poorly-performing engine.

Regular oils are not as refined as synthetic oils. Most cheap conventional oils contain large particles, dirt, and grit that will only make your engine dirty. A dirty engine wears quickly as the different components will soon grind each other out.

Regular oil endangers the ecosystem

Regular oil will never be broken down into smaller molecules and thus won't disappear like other organic waste materials. These oils will only remain in the area creating a toxic mix that will take forever to decompose.


No doubt that regular oil is cheaper than synthetic oils. This may be the only reason why people keep using it anyway. But when you add the cost of more frequent oil changes, engine checks, and repairs or engine parts replacement due to regular oil use, it certainly smart to invest in synthetic engine oil.


About the Author JamesL Davis

James is a certified auto technician specializing in commercial vehicles. With 30 years of experience under his belt, James has encountered almost every type of automotive issue there is! Besides his day job at the repair shop, he is also an amateur race car driver.

follow me on:

Leave a Comment: