Synthetic Oil Vs. Conventional Oil: Which is Better and What Are The Benefits of Each?

Main differences between synthetic oil and conventional oil, price, longevity, cleaning, and engine performance

The engine likes synthetic oil more. Synthetic oil deals with extreme temperatures way better and reduces friction and wear. The chemicals it uses raise its prices, though, so they're more expensive. Still, conventional oil is still good for older, less demanding engines; it's great material and will treat your car just fine, you'll just have to plan a schedule to change it more often. Finally, the best oil depends on your driving habits, car's age, and budget.

Should I use synthetic oil in my high-mileage car?

Whether synthetic oil is right for your high-mileage car depends on a few factors:


  • Less wear and tear: Synthetics are good at protecting parts, potentially lengthening engine life. This type of benefit goes beyond engine oil; you'll also notice less wear and tear for many other components using synthetic fluids. For example, a synthetic differential fluid will be better than a conventional one.

Lack of oil means lack of lubrication and damage to car components, especially gears

  • Improved performance: Less friction means smoother operation and even better fuel economy.

  • Longer oil change intervals: Some synthetics can go 7,500-10,000 miles between changes, saving time and money.


  • Cost: Synthetic oil is significantly more expensive than conventional at first glance. Although, they're cost-beneficial down the road.

  • Seals and leaks: In rare cases, switching to synthetic can worsen existing leaks due to their cleaning properties. This only happens in situations where the previous oil brand had seal swelling additives.

Synthetic oil can dissolve buildup sludges, causing oil to leak from leaky seals

  • Unnecessary for old engines: If your car's engine is in good condition with low mileage, conventional oil might suffice. Although this might be common for most vehicles, consider chatting with your mechanic to see how it fits your case.

Here's our advice

  • Check your owner's manual: Follow the manufacturer's oil recommendations for viscosity and type (conventional, synthetic, blend). Your trusted mechanic can also make recommendations based on your specific driving habits.

  • Consider your car's condition and driving habits: If your car runs well and you drive primarily in moderate conditions, conventional might be fine. But if you have a higher mileage engine, drive in extreme temperatures, or prioritize performance and longevity, synthetic could be a wise investment.

  • Consult a mechanic: They can assess your car's specific needs and recommend the best oil based on its condition and your driving habits. Always take the mechanic's recommendations seriously since their goal is to get your car safe, comfortable, and reliable. OEM specifications typically get the vehicle out of warranty.

In any way, you should understand how your car responds to different types of oil and plan based on professional recommendations.

Does conventional oil last longer?

No, conventional oil does not last longer than synthetic oil; it's actually the other way around. Synthetic oil typically lasts longer than conventional oil, earning some advantages:

  • Longer oil change intervals: Generally, synthetic oil is recommended to be changed every 5,000-7,500 miles, while conventional oil is every 3,000-5,000 miles.

  • Less damage from overheating: Synthetic oil maintains its viscosity better in extreme temperatures, providing superior lubrication and protection. Consequently, it avoids engine overheating better.

Synthetic oil can avoid engine overheating. Therefore, it can also avoid oil warning light in that case

  • Reduced friction and wear: This leads to less engine wear and tear, potentially extending engine life.

While conventional oil is cheaper, they don't last really long. So, you'll find yourself changing the oil more frequently, which, if you put it on paper, might end up costing more overall.

However, in some cases, conventional oil might be appropriate:

  • Older cars with high mileage: If your engine is already worn and using oil, switching to synthetic may not be beneficial.

Using synthetic oil in older engines with high mileage that were using conventional oil before might be a bad idea and cause leaks or other problems

  • Cars rarely driven: If you only drive your car a few thousand miles per year, the longer life of synthetic oil may not be worthwhile.

  • Tight budget: Conventional oil is significantly cheaper than synthetic.

What happens if you put conventional oil in a car that requires synthetic?

Putting conventional oil in a car that needs synthetic won't cause big damage, but isn't good in the long run. Here's what you need to know:

Immediate impacts

  • Reduced engine protection: Conventional oil doesn't offer the same level of protection as synthetic at high temperatures and under heavy loads. This can lead to increased wear and tear on engine components.

  • Shorter oil change intervals: Since conventional oil breaks down faster, you'll need to change it more frequently than the recommended interval for synthetic oil.

  • Potential decrease in fuel efficiency: Increased friction from using conventional oil can slightly reduce your car's fuel economy.

Long-term impacts

  • Increased sludge build-up: Conventional oil leaves more deposits in the engine over time, which can eventually lead to sludge build-up. This can clog engine parts and reduce performance.

Engine filled with oil sludges due to conventional oil being old

  • Higher risk of engine damage: The reduced protection and increased wear and tear can eventually lead to serious engine problems, requiring costly repairs.

What to do if you accidentally use conventional oil

  • Don't panic: It's not the end of the world. Just get your oil changed as soon as possible and switch back to the recommended synthetic oil.

  • Consider getting the engine flushed: This will remove any residual conventional oil and help prevent sludge build-up.

  • Stick to the recommended oil from now on: Following the manufacturer's recommendations for oil type and change intervals will ensure optimal engine performance and longevity.

Remember, while using conventional oil in a car designed for synthetic won't immediately destroy your engine, it's not a good practice and can lead to problems down the road. It's always best to stick with the recommended oil type for your car to ensure its health and longevity.

Is it OK to switch from conventional to synthetic oil?

Absolutely! In fact, switching from conventional to synthetic oil is good for your car's engine. Here's why:

Benefits of Synthetic Oil

  • Superior lubrication and protection: Synthetic oil's uniform molecules resist breakdown at extreme temperatures and reduce friction, minimizing wear and tear on engine components. Think of it like a smoother, more protective coating for your engine's vital parts.

  • Extended oil change intervals: Unlike conventional oil that needs changing every 3,000-5,000 miles, synthetic oil can last up to 7,500-10,000 miles between changes, saving you time and money in the long run.

  • Improved fuel efficiency: Reduced friction from synthetic oil can lead to slightly better fuel economy, giving you more miles per gallon. Every little bit counts, right?

  • Better performance: Smoother engine operation thanks to synthetic oil's superior lubrication can translate to a more responsive and powerful driving experience.

Things to Consider

  • Cost: Synthetic oil is generally more expensive than conventional oil. However, the extended oil change intervals and potential fuel savings can often offset the initial cost.

  • Older engines: In rare cases, switching to synthetic oil in a very old engine with existing leaks or worn seals could potentially worsen the issue. Consult a mechanic if you're unsure about your specific car.

  • Manufacturer's recommendations: Always check your car's owner's manual for the recommended oil type and viscosity. While switching to synthetic is generally safe, it's best to follow the manufacturer's guidelines for optimal performance.

In short, synthetic oil is better. If you're looking to give your engine the best care and protection, switching to synthetic oil is wise. However, if you're on a tight budget or have a very old car with potential issues, conventional oil might still be fine.

How long does synthetic vs conventional oil last?

Synthetic Oil:

  • Oil Change Intervals: 5,000 - 15,000 miles (depending on brand and driving conditions)

  • Overall Lifespan: Can protect engines for hundreds of thousands of miles with proper maintenance.

Conventional Oil:

  • Oil Change Intervals: 3,000 - 5,000 miles (depending on brand and driving conditions)

  • Overall Lifespan: Generally protects engines for less than synthetic, but still offers protection for tens of thousands of miles with proper maintenance.


This article discussed the difference between synthetic and conventional car oil. The discussions mentioned the benefits of each oil type, including how long they last in the engine, prices, pros and cons. The article explained specific cases, like how using both oil types in older engines can matter. Finally, the choice depends on your driving habits, budget, and your car's specific needs. Remember, keeping your engine well-lubricated with any oil is the most important.

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