Can You Mix Synthetic and Conventional Oil? The Truth Revealed

Motor oil is a crucial component of an engine, helping it run efficiently and maintain optimal performance. When it comes to choosing the right type of oil, drivers are often left confused about whether to use synthetic or conventional oil.

Switching between the two oils can be expensive and impractical, prompting many drivers to ask whether they can mix synthetic and conventional oil.

Yes, it is possible to mix synthetic and conventional oil in an engine. Mixing the two types of oil will not harm the engine or affect performance negatively.

The topic of mixing synthetic and conventional oil often sparks debate among vehicle owners. Many wonder if it’s safe to combine these two types of oil in a car or motorcycle. This article aims to provide valuable information on this subject, addressing common concerns and misconceptions.

First, let’s discuss the compatibility of synthetic and conventional oil. In general, these two types of oil can be mixed without causing harm to your engine. This is because both synthetic and conventional oils share similar base components, making them compatible with one another. So, whether you’re driving a car or riding a motorcycle, combining these oils should not pose a problem.

Next, let’s consider the effects of mixing synthetic and regular oil in gear systems. Just like with engine oil, synthetic and conventional gear oils can be combined without causing damage. The key is to ensure that the mixed oils meet the manufacturer’s specifications for your vehicle’s gear system.

Now, let’s address the question of mixing synthetic and regular 2-cycle oil. While it’s generally safe to mix these oils, it’s crucial to follow the manufacturer’s recommendations for the proper oil-to-fuel ratio. This will help maintain optimal engine performance and prevent potential issues.

Lastly, it’s worth noting the potential consequences of mixing synthetic and conventional oil. While it’s not inherently harmful, doing so may dilute the benefits of synthetic oil, such as improved engine protection and extended oil change intervals. To maximize the advantages of synthetic oil, it’s best to use it exclusively.

Synthetic And Conventional Oil

Synthetic and conventional oils have differences that make them unique. Synthetic oil is a laboratory-made lubricant that often outperforms conventional oil in high-stress conditions.

Conventional oil, on the other hand, is made from refined crude oil and contains additives. Synthetic oil is costlier than conventional oil, but its performance is superior.

Another difference is that synthetic oil lasts longer than conventional oil and is better at preventing engine wear.

Mixing them is generally not recommended, as the benefits of synthetic oil will become diluted. It’s essential to understand the differences between these two oils before selecting the best option for your vehicle.

Can You Mix Synthetic And Conventional Oil?

Mixing synthetic and conventional oil may seem like a good idea for those on a tight budget, but it could result in serious engine damage. The different molecular structures of the oils may cause them to clash and reduce their effectiveness.

Mixing oils could also cause a sludge buildup in the engine. While some mechanics are okay with mixing oils, others warn against it, stating that the potential risks are not worth it. Synthetic and conventional oils are designed to complement specific engines, so it’s best to stick to one type.

Mixing oils could cause unnecessary expenses down the road, so it’s better to avoid it altogether.

Factors To Consider Before Mixing Synthetic And Conventional Oil

Compatibility of Oils

Before mixing synthetic and conventional oil, ensure that the oils are compatible. Both types of oil should share similar base components to prevent any adverse effects on the engine.


The viscosity of the oils should be compatible to maintain proper lubrication and engine performance. Mixing oils with different viscosities may lead to inadequate lubrication and increased engine wear.

Vehicle Manufacturer’s Recommendations

Always follow the vehicle manufacturer’s recommendations for oil type and viscosity. Mixing oils that do not meet these specifications may void warranties and lead to engine damage.

Oil Change Intervals

Adhering to the recommended oil change intervals is crucial, as mixing synthetic and conventional oil may affect the oil’s performance over time.

Engine Age and Condition

Consider the age and condition of the engine before mixing oils. Older engines may have more wear and require a specific oil type to maintain performance and prevent further damage.

Engine Sludge

Mixing synthetic and conventional oil in an engine with existing sludge buildup may exacerbate the issue. In such cases, it’s best to consult a professional mechanic for advice.

Climate and Driving Conditions

Take into account the climate and driving conditions in your area. Synthetic oil performs better in extreme temperatures and harsh conditions, while conventional oil may suffice in milder environments.

Temperature Range

Mixing oils may affect their performance in extreme temperatures. Ensure that the mixed oil can handle the temperature range in your region.

Cost and Availability

Evaluate the cost and availability of synthetic and conventional oil in your area. Mixing oils may not be cost-effective if one type is significantly more expensive or difficult to obtain.

Long-term Savings

Consider the potential long-term savings of using synthetic oil exclusively, as it may offer better engine protection and extended oil change intervals.

How To Switch From Synthetic To Conventional Oil Or Vice Versa

Switching from synthetic to conventional oil or vice versa is a straightforward process. Follow these steps to ensure a smooth transition:

1. Consult your vehicle’s owner’s manual: Before making any changes, consult your vehicle’s owner’s manual for the recommended oil type and viscosity. Ensure that the oil you plan to switch to is compatible with your vehicle’s engine.

2. Check engine condition: Inspect your engine for any signs of wear, sludge buildup, or leaks. If you find any issues, address them before switching oil types.

3. Drain the old oil: Warm up your engine for a few minutes to help the oil flow more easily. Then, turn off the engine, place a drain pan under the oil drain plug, and remove the plug to drain the old oil. Be cautious, as the oil may be hot.

4. Replace the oil filter: Remove the old oil filter using an oil filter wrench, and lubricate the gasket of the new filter with a small amount of fresh oil. Install the new filter.

5. Add the new oil: Pour the new oil (either synthetic or conventional) into the engine, following the manufacturer’s recommended oil capacity. Use a funnel to prevent spills.

6. Check the oil level: After filling the engine with the new oil, wait a few minutes for the oil to settle, then check the oil level using the dipstick. Add more oil if necessary to reach the correct level.

7. Start the engine: Start your engine and let it run for a few minutes to circulate the new oil. Check for any leaks around the oil filter and drain plug.

8. Dispose of the old oil: Properly dispose of the used oil and filter at a designated recycling facility or auto parts store.

Remember to monitor your engine’s performance and oil consumption after switching oil types. If you notice any issues, consult a professional mechanic for advice.


Incorporating synthetic and conventional oils might seem like a good idea at first, but it’s best to stick to one type for optimal performance. Each of these oils has its unique properties and strengths that work together to provide the best results.

Mixing them together can cause problems like reduced functionality, engine damage, and reduced fuel economy. While synthetic oil is more expensive than conventional, it offers more benefits, like prolonged engine life, limited emissions, and maintenance. The use of synthetic oil in vehicles is rapidly increasing as more people realize the benefits it offers.