Synthetic vs Conventional Oil: Which Is Better For Engines?

When it comes to choosing between synthetic and conventional oil for your engine. The decision involves considering the pros and cons of each lubricant type. Having worked closely with Thompson Sales in the past. I’ve seen drivers with vehicles that clock in heavy mileage opt for synthetic oil. Its artificially made chemical compounds are tailored to prevent breaking down even under harsh conditions. Making oil changes a less frequent concern. This is especially beneficial when rebuilding engines, as the right oil can substantially prolong the life of an engine.

On the other hand, some prefer sticking to the traditional conventional oil, particularly for older vehicles. Its petroleum molecules have been lubricating engines since cars were first invented. Conventional oil does the job for engines that aren’t subjected to extreme conditions. Yet, the introduction of semi-synthetic oils – a hybrid of sorts – has complicated the debate, providing more options. These serve as a compromise, offering added protection without the commitment to full synthetic. Especially for those in-between on the matter.

Drawing from my expertise, the choice really boils down to the engine’s requirements and the driver’s preferences. Being informed about these options has always been a cornerstone of my consultations with clients regarding their engine’s health.

What Is Synthetic Oil?

Synthetic oil is a high-performance lubricant composed of artificially made chemical compounds. When examined under a microscope, it reveals that each of its millions of molecules are of the same size and possess the same structure. Unlike conventional oil which consists of mineral oil with molecules of different shapes, different sizes, and different structures. Options such as fully synthetic and synthetic blend oils incorporate multiple base types. But a truly synthetic base stock is uniquely designed, molecule by molecule, and generally springs from non-petroleum sources. 

Loaded with additives aimed at reducing degradation, synthetic oils offer superior protection, compared to conventional motor oil, and their types boast distinctly different properties suitable for diverse applications. For instance, as an automotive service professional. I often suggest polyalphaolefins (PAO), a common reference point for high-quality synthetic oils, for high-performance engines which demand robust oil stability.

Synthetic vs. Conventional Oil

When it comes to the health and longevity of vehicles. The debate between synthetic oil and conventional mineral oil is ongoing. As a Technical Services Manager in Machinery Lubrication, I’ve scrutinized these engine oils through the microscope of industry experience to understand their certain properties and performance properties. Synthetic oils are designed with formulations that cater to modern engines’ demands, offering superior performance over mineral oils.

 They display impressive shear stability, lower deposit formation, and reduced volatility. Moreover, their cold-temperature pumpability and oxidation resistance ensure that the oil maintains its fluidity at low temperatures and its viscosity protection under extreme engine loads, resulting in less engine wear.

What sets these oils apart are the physical properties and chemical properties. While conventional oils, certified by organizations like American Petroleum Institute (API) and International Lubricant Standardization and Advisory Committee (ILSAC). Meet basic specifications, synthetic oils often exceed them due to their enhanced rheological changes and thermal stability. Synthetic blend oil, a mixture of synthetic and conventional oils. Can be a middle ground for those not ready to commit to full synthetics.

Though I’ve perused countless Consumer Reports and diligently followed manufacturer recommendations, the advancement in synthetic oil technologies is evident. It’s true that synthetics may exhibit disadvantages such as being more expensive upfront; however, they offer long-term savings through extended oil change intervals and better fuel economy. My personal experience, backed by decades in the field, confirms that while conventional oils have served well in the past. The future seems slicker and more efficient with synthetics.

Advantages and Disadvantages of Synthetic Oil

Advantages of Synthetic Oil

  • Synthetic oil advantages include a higher-quality base oil and additive package. Elevating engine oils work to a more meaningful and significant level over conventional lubricants.
  • Utilizing synthetics such as PAOs ensures superior performance, with less chemical degradation and resistance to oxidation and harmful combustion byproducts.
  • In comparison to mineral oils, synthetics are less prone to creating sludge, varnish, or deposits, essentially reducing corrosion and maintaining the engine’s integrity over time.
  • Synthetic oils boast an impressive viscosity index, minimizing the risk of viscosity change even under extreme temperature changes. Which could otherwise impair engine performance.
  • At both startup and operating conditions, synthetic lubricants maintain a consistent film thickness on metal surfaces, reducing friction and wear.
  • Under extremely low temperatures, synthetics remain pumpable and effectively circulate.Within the engine, preventing lubricant starvation conditions and ultimately engine failure.
  • Synthetic oils are less volatile, reducing loss through the exhaust stream and consequent atmospheric pollution. While also requiring less makeup oil and fewer oil changes over their lifespan.
  • They often exceed manufacturer’s recommended change interval, which is beyond what is typically expected with conventional oil and brands.

Disadvantages of Synthetic Oil

  • The cost of synthetic oil is significantly higher than that of conventional oil. Making it a less economical choice up front.
  • In cold storage conditions, synthetic oils may be more prone to additives precipitation. Causing stratification which can lead to complete separation.
  • Synthetic oils, particularly multi-grade motor oils, can face challenges in maintaining fuel economy at highway speeds due to separation issues.
  • There’s a potential risk for viscosity friction and shear-induced temporary viscosity thinning, owing to the specialized additive components in synthetic options. Which enhances engine performance but also may exhibit downfalls in these aspects.

Is Synthetic Oil Worth the Cost?

Synthetic oil may come with a higher initial cost compared to conventional oil. But when considering the long-term savings and protection it offers, it’s worth every penny. By protecting your engine’s components and extending the service life of your vehicle’s engine. You are not only saving money on frequent oil changes, but you’re also investing in the longevity of your car. Vehicle manufacturers often recommend synthetic oil for its superior lubrication and engine protection qualities.

 If you’re someone who plans on keeping your car for the long haul. Investing in premium engine’s lubrication components with synthetic oil can help extend the life of your engine. However, if you’re planning to sell your car before reaching its normal end of life. The benefit of expensive synthetics may be less significant in time. For those who subject their vehicles to extreme temperatures, heavy loads, or frequent cold starts, synthetic oil can save your engine from harm and impaired engine cooling that might lead to engine failure. 

Conventional mineral oil may suffice if you closely follow your vehicle’s manufacturer’s recommended oil change intervals and drive under normal conditions. But for any exceptions, synthetic oil is your safest bet.

Synthetic Engine Oils: Digging Deeper

When we analyze synthetic oil, we’re discussing a product developed for motor vehicles with the most refined base oils available – often surpassing the American Petroleum Institute’s (API) stringent categories. Unlike petroleum crude oil, synthetic oil can be broken into Group IV (e.gPolyalphaolefins or PAOs) and Group V (Esters) – the base stock oils that provide a chemical makeup purer than what we term as conventional oil.

 These are often more refined, which wards off oxidation and provides remarkable thermal stability. Benefits extend to lower volatility contributing to better heat dissipation. Pour point functionality, and resilience to reaction with acids and alcohols.

 Even in my personal history with vehicles, my companions in the lab and over the road have noticed a significant decrease in sludge and deposit buildup in engines running on fully synthetic oil compared to those using mineral oil.

When Synthetics Always Makes Sense

Synthetic oil is an investment with a clear payoff for those pushing their engines to the limit – be it luxury sedans or sports cars. Whether you’re an auto enthusiast climbing long hills. A high-performance driving fan, or someone operating in worst-case scenarios quite regularly, the synthetic’s endurance to maintain consistent oil films under high loads delivers an indisputable competitive edge.

 Premium synthetics come packed with additive packages designed to sustain engine performance over the last mile. Reducing wear rates and sustaining reliability even at -40°C or -40°F, a fact that every driving public with high-mileage engines, towing habits, or a penchant for motor sports will value. The math behind the decision hinges on a cost/benefit analysis. The safety margin these oils provide against a close call in frequent short commutes, frequent cold starts, or extreme temperatures justifies the cost.

 A good judgment call, backed by facts, tilts the scales in favor of synthetics when it comes to ensuring engine reliability and making a sound decision amidst ambiguity and uncertainty under harsh climate conditions.

Is synthetic oil better for my engine than conventional oil?

Yes, synthetic oil is generally considered as a better option for your engine than conventional oil. The synthetics are more chemically stable, do not oxidize or acidify as easily, and thus, do not break down or lose their protective qualities rapidly under high temperatures.

 Unlike conventional oils, which rely on the more basic chemistry of mineral oils, full synthetic oils, like Mobil 1™ advanced full synthetic motor oils. Boast a robust additive system that elevates the performance benefits significantly. Synthetic blend motor oils are a move towards this advantage, offering some of synthetic’s chemistry without incurring the full cost. 

Personal experience and expertise in this field have shown me time and again: if you desire the utmost in lubrication performance and engine protection, full synthetics are the way to go.

Main Types of Motor Oil

Full Synthetic Motor Oil

Full Synthetic Motor Oil stands as a testament to modern oil technology. Refined meticulously, it undergoes a rigorous process to eliminate impurities and enrich it with a cocktail of additives. These additives, ranging from cleansers to anti-oxidizers, work in tandem to fortify the oil, ensuring peak performance across a spectrum of driving conditions.

Conventional Motor Oil

Conversely, Conventional Motor Oil represents a more traditional approach. Derived through simpler processes, it may contain a higher degree of impurities compared to its synthetic counterpart. Nevertheless, this doesn’t necessarily equate to inferior performance. Conventional oil remains a steadfast choice for many drivers, particularly those with simple engine designs or who adhere to ordinary driving styles.

Synthetic Blend Motor Oil

In the middle ground lies Synthetic Blend Motor Oil. This blend offers a compromise, incorporating some benefits of synthetic oil while costing less than its fully synthetic counterpart. While not as potent as full synthetics, it still provides enhanced protection compared to conventional oils.

Semi-Synthetic Motor Oil

Finally, we have Semi-Synthetic Motor Oil, often referred to as synthetic blend oil. This blend strikes a balance, harnessing the lubricating properties of synthetic oils while retaining elements of conventional oil. By blending these two ends of the petroleum product spectrum, manufacturers can tailor the oil to specific needs, whether it’s engine protection or optimal performance in extreme temperatures.

In my experience, the choice between synthetic and conventional oils depends on various factors: vehicle type, driving habits, and environmental conditions. While full synthetic oils boast longer oil change intervals and enhanced performance, conventional oils remain a reliable and cost-effective option for many drivers.

Each type of oil serves its purpose in the automotive world, catering to a diverse array of needs and preferences. Whether you’re cruising through warmer climates in a Buick or navigating icy roads in a GMC, understanding the distinctions between synthetic and conventional oils empowers you to make informed decisions for your vehicle’s needs.

Better Performance in Extreme Temperatures

Now, let’s delve into a scenario where your car faces extreme temperatures, whether it’s the blistering heat of summer or the bone-chilling cold of winter. Conventional oil tends to thicken in such conditions, resembling sludge rather than the lifeblood your engine needs. In the cold, it moves as slowly as a slug, leaving vital engine parts temporarily unprotected during startup. 

In contrast, synthetic oil flows easily and quickly, even in the most extreme temperatures. When your engine is scorching hot, synthetic oil outperforms conventional oil, offering superior heat resistance. It prevents the dreaded turbo coking, where heat cooks the oil inside the turbo, causing harmful buildup and deposits.

 Synthetic oil, with its ability to withstand high temperatures, ensures your engine remains well lubricated and protected even under the most demanding conditions.

Maximizes Fuel Economy

When it comes to maximizing your vehicle’s fuel economy, the choice between synthetic and conventional oil plays a crucial role. Picture this: on a frosty morning, conventional oil settles like molasses, making your engine work harder during startup. 

This sluggishness can persist in cold weather, impacting fuel efficiency. Conversely, synthetic oil, with its ability to flow freely even in frigid conditions, ensures a smoother start-up, thereby maximizing fuel economy from the get-go.

Does Synthetic Oil Have Longer Oil Change Intervals Than Conventional Oil?

One of the most common questions surrounding synthetic and conventional oil is whether synthetic oil indeed boasts longer oil change intervals. Generally, synthetic oil does offer longer oil change intervals compared to conventional oil. However, it’s essential to consider various factors such as driving style, conditions, and manufacturer recommendations.

 While some synthetic motor oil brands may advertise extended intervals, it’s crucial to follow the guidelines provided by your vehicle’s manufacturer. The Mobil 1 lineup, known for its high-quality full synthetic motor oils, often provides extended intervals, sometimes lasting up to a full year.

What Is the Difference Between a Full Synthetic Oil and a Synthetic Blend?

Understanding the distinction between full synthetic oil and a synthetic blend is key to making an informed decision. Full synthetic motor oils consist of the highest quality base oil combination, coupled with a tailored additive system. 

On the other hand, synthetic blend motor oils blend high-quality synthetic base oils with conventional base oils, offering a compromise between performance and cost. While both provide better protection compared to conventional oils, full synthetics offer additional performance benefits thanks to their superior base oil and additive composition.

My Car Doesn’t Require Synthetic Motor Oil.

Making the switch from conventional to full synthetic motor oil is indeed possible and often beneficial for your engine’s longevity. Even if your vehicle doesn’t explicitly require synthetic oil, switching is generally compatible, especially for high mileage vehicles. However, it’s essential to follow proper procedures, including engine flushing if necessary, to ensure compatibility and optimal performance.

 Mobil 1 oils, renowned for their quality and performance, can help clean up your engine, particularly in cases of poorly maintained or infrequently serviced vehicles. Adhering to OEM’s recommended maintenance practices, including frequent oil changes, can prevent the buildup of sludge and deposits, keeping your engine running smoothly and efficiently


In conclusion, the debate between synthetic and conventional oil for engines is nuanced, but each type offers distinct advantages. While synthetic oil provides superior performance, particularly in extreme temperatures, and offers longer oil change intervals, conventional oil remains a reliable and cost-effective option for many drivers.

 Understanding the needs of your engine and considering factors like driving habits and environmental conditions are crucial in making the right choice. With my expertise and experience in the field, I’ve witnessed the impact of this decision on engine health firsthand.

 Whether you opt for the advanced protection of synthetic oil or the tried-and-true reliability of conventional oil, prioritizing regular maintenance and informed decision-making ensures the longevity and efficiency of your vehicle’s engine.


Is synthetic oil good for all engines?

This being said, however, it is still not recommended to use synthetic oil in engines that have experienced significant actions – specifically, those that have reached around 75,000 miles on the odometer.

What is the disadvantage of synthetic engine oil?

A few disadvantages of synthetic oil to be aware of include: Probably the most glaring downside of synthetic oil is the cost. The price of synthetic oil is around two to four times the price of conventional oil. Synthetics may be more prone to additive precipitation during cold storage conditions.

Is synthetic engine oil the best?

Synthetic oils are specifically manufactured to provide consistent, superior performance. Their main advantage over mineral oils is that they protect the engine across a far wider range of temperatures – up to an engine’s maximum temperature.

Does synthetic oil improve engine efficiency?

Synthetic oil provides much better cold-flow ability than conventional oil, which means it flows in the engine much faster in cold temperatures. This reduces engine wear during startup, which can contribute to better mileage over time.

Does synthetic oil clean your engine?

Synthetic oils, such can help clean your engine, prevent sludge buildup, and improve fuel economy. Synthetic oils have fewer impurities than conventional oils, thereby increasing the overall longevity and performance of your engine. Less sludge means smoother operation from the get-go.