Synthetic oil is a popular topic in the automotive world. Are you curious about what synthetic oil is and how it can benefit your engine? At WHAT.EDU.VN, we provide clear and concise answers to your questions. This guide will explore the definition of synthetic oil, compare it to conventional oil, and outline its advantages and disadvantages. Discover how synthetic lubricants can enhance your vehicle’s performance and longevity. Learn about motor oil, engine wear, and lubrication.
1. Understanding What Is Synthetic Oil
Synthetic oil is a lubricant crafted from artificially made chemical compounds. These compounds are engineered through a process of breaking down and rebuilding petroleum molecules. Unlike conventional oil, which is derived from refined crude oil, synthetic oil boasts a more uniform molecular structure.
Under a microscope, synthetic oil reveals millions of molecules of nearly identical size and structure. In contrast, conventional oil displays a diverse array of molecules with varying shapes and sizes. Synthetic oil can be either fully synthetic or a synthetic blend, offering versatility in its application.
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1.1. Full Synthetic Oils Explained
Full synthetic oils utilize a synthetic base stock meticulously designed molecule by molecule without the use of petroleum. These oils include additives specifically formulated to aid in the oil’s degradation process. The result is a high-performance lubricant that offers superior protection and longevity.
1.2. Synthetic Blend Oils: A Balanced Approach
A synthetic blend combines conventional motor oil with synthetic base stocks. This blend offers enhanced protection compared to using conventional oil alone. By incorporating synthetic components, the blend provides improved performance and durability, striking a balance between cost and effectiveness.
1.3. Types of Synthetic Oils
Various types of synthetics exist, each with distinct properties and applications. Polyalphaolefins (PAO) are the most commonly used synthetics in automotive service due to their balanced properties and cost-effectiveness. For simplicity, this article will primarily reference PAOs when discussing synthetic oils.
2. Synthetic vs. Conventional Oil: A Detailed Comparison
Most vehicles can use either synthetic or conventional mineral oil, provided they meet the specifications set by the American Petroleum Institute (API) and the International Lubricant Standardization and Advisory Committee (ILSAC). However, synthetic oils are often marketed for their superior performance compared to conventional oil.
This superior performance may be limited to specific properties. Some formulations of conventional mineral oils may even outperform synthetic oils in certain aspects. It’s essential to consider all factors when choosing the right oil for your vehicle.
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2.1. Comparative Studies: Synthetic Oil’s Edge
Numerous studies have compared synthetic oil to conventional mineral oil. The American Automobile Association (AAA) conducted notable research using certified labs and American Society for Testing and Materials (ASTM) standardized test methods. These tests examined differences in engine oils marketed as conventional versus those marketed as full synthetic.
2.2. Key Findings from AAA’s Research
AAA’s research revealed that synthetic oils outperformed conventional oils by an average of 47 percent in the conducted tests. The tests evaluated critical properties such as shear stability, deposit formation, volatility, cold-temperature pumpability, oxidation resistance, and oxidation-induced rheological (viscosity) changes.
2.3. Synthetic Oil’s Growing Popularity
Synthetic oil is rapidly becoming the norm, with nearly 70 percent of new cars in the 2019 model year using either fully synthetic or a synthetic blend oil, according to Consumer Reports. Despite the increasing prevalence of synthetic oils, it remains crucial to follow manufacturer recommendations for oil changes.
2.4. The Importance of Following Manufacturer Recommendations
Michael Calkins, Technical Services Manager for AAA, advises that “Semi- or full-synthetic oils are required for most newer cars, but it is vital that the automaker’s recommendations be followed, or accelerated engine wear and other problems could result.” Adhering to these guidelines ensures optimal engine performance and longevity.
2.5. Disadvantages of Conventional Oil
The advancement of synthetic oil has highlighted the limitations of conventional oil. While conventional oil adequately lubricates your car’s engine in many cases, it has potential disadvantages. These include marginal fluidity at extremely low temperatures, thermal and oxidative stability, and viscosity protection at high engine loads and temperatures.
3. Advantages and Disadvantages of Synthetic Oil
Switching to synthetic motor oil offers significant advantages over conventional oil. Let’s explore the pros and cons of synthetic lubricants to help you make an informed decision.
3.1. Key Advantages of Synthetic Oil (PAOs)
When comparing synthetic oils (PAOs) to conventional engine oils, several advantages stand out. Note that the benefits listed below assume a similar additive package between the two options, which is rarely the case. Most synthetic lubricant formulations for automobiles have superior additive packages, making the comparison more complex.
- Resistance to Chemical Degradation: Conventional mineral oils are more prone to chemical degradation (oxidation) compared to synthetics when exposed to combustion byproducts, fuel contamination, water contamination, metal particles, acids, pro-oxidants, and extreme heat.
- Higher Viscosity Index: Synthetics have a naturally higher viscosity index, meaning their viscosity changes less as temperature fluctuates during engine startup and operation.
- Improved Low-Temperature Performance: Mineral oils are more likely to thicken at extremely low temperatures, hindering their ability to circulate effectively within the engine.
- Lower Volatility: Synthetic engine oils are generally less volatile than mineral oils, resulting in less oil loss to the engine’s exhaust stream and reduced atmospheric pollution.
- Extended Lifespan: Synthetic oil has a longer lifespan than conventional oil, with recommended change intervals around 5,000 to 7,000 miles, and some brands touting intervals of 15,000 to 25,000 miles.
3.2. Disadvantages of Synthetic Oil
Despite the numerous benefits, synthetic oil has a few drawbacks to consider:
- Higher Cost: The price of synthetic oil is typically two to four times higher than conventional oil.
- Additive Precipitation: Synthetics may be more prone to additive precipitation during cold storage, leading to the separation of certain additives.
- Slightly Lower Fuel Economy: Multi-grade motor oils using synthetics may exhibit slightly less fuel economy at highway speeds compared to mineral oil.
| Advantages and Disadvantages of Synthetic Oil |
| :————————————————- | :————————————————- |
| Advantages | Disadvantages |
| Resistant to oxidation and chemical degradation | More expensive |
| Withstands temperature extremes better (cold and hot) | Possible additive precipitation/separation |
| Flows better at cold temperatures | Slightly lower fuel economy at highway speed |
| May produce less sludge and surface deposits | |
| Longer oil change intervals | |
| More robust film thickness at higher temperature and higher loads | |
4. Is Synthetic Oil Worth the Cost?
Determining whether synthetic oil is worth the cost involves considering various factors. The price of synthetic or synthetic blends isn’t always straightforward. “It is very difficult to generalize because of the many differences in oil brands and formulations. A quart of modern semi- or full-synthetic oil usually costs somewhere between four and 10 dollars, although some special blends can cost even more,” explains Calkins.
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4.1. Cost Comparison: Conventional vs. Synthetic Oil
As of 2019, five quarts of conventional oil cost approximately $28, and an oil change with conventional oil costs about $38, according to a survey of AAA’s approved auto repair facilities. In contrast, five quarts of full synthetic oil cost about $45, while an oil change with full synthetic oil costs about $70. Switching from conventional to synthetic costs the average driver about $64 per year or $5.33 per month.
4.2. Long-Term Savings with Synthetic Oil
While a manufacturer-approved conventional oil won’t harm your engine, investing an extra $30 per month in synthetic oil can save you money long-term by protecting your engine’s components. You may also offset some of the extra costs by changing your oil less frequently.
4.3. Oil Change Frequency: Synthetic vs. Conventional
The change frequency of synthetic oil is longer, with most brands recommending an oil change at around 5,000 to 7,000 miles (up to 25,000 miles depending on the brand). Conventional oil changes are recommended at 3,000 to 5,000 miles. If using synthetic oil for extended intervals, upgrade your oil filter to match the oil’s service life.
4.4. Expert Opinion: Is Synthetic Oil Better?
“In general, yes – provided the automaker’s viscosity grade and other oil requirements are adhered to,” says Calkins. While mineral oil provides adequate lubrication, synthetic oil better protects your engine with higher-quality, more refined base oils.
4.5. Following Manufacturer Recommendations
“Always use at least the type of oil recommended by your vehicle’s manufacturer. If your car only calls for conventional oil, the slightly higher cost of a semi-synthetic product will provide better engine protection. Regardless of the oil used, always follow the vehicle manufacturers’ recommended oil change intervals,” advises Calkins.
4.6. Consider Your Car Ownership Plans
Think about how long you plan to own your car. Investing in premium lubrication may slightly extend your engine’s life. However, if you plan to sell your car long before engine failure is likely with mineral oil, the benefit of using expensive synthetics is transferred to the next owner.
4.7. Exceptions to the Rule
Certain exceptions exist, particularly when exposing an engine to worst-case scenarios long before its normal end of life. These scenarios include extreme temperatures, neglected oil changes, heavy loads, frequent cold starts, frequent short commutes, and impaired engine cooling.
5. Synthetic Engine Oils: Digging Deeper
Synthetic oil used in motor vehicles is refined from base oils or base stock oils. The American Petroleum Institute (API) categorizes base oils into five groups; the first three are oils refined from petroleum crude oil. Group IV base oils are fully synthetic, and Group V contains all base oils not in the first four groups. The API identifies Polyalphaolefins (PAOs) and Esters (Diester and Polyol) as the most common base oils used for synthetic oil.
5.1. Polyalphaolefins (PAOs)
PAOs are the most common type of synthetic base oils due to their moderate price and minimal negative attributes. PAOs are Group IV base oils and are similar to mineral oil in their chemical makeup, but their built structure makes them purer. Benefits include improved oxidation and thermal stability, low volatility, good heat dissipation, a low pour point, and the absence of waxy molecules.
5.2. Esters
Esters, a Group V base oil, are made from ester oils created from the reaction of acids and alcohols with water molecules splitting off. The most common esters used for synthetic motor oil are diesters and polyol esters. Diesters are commonly used as an additive with PAO base stock oil. Esters have high thermal stability and excellent low pour point characteristics but poor hydrolytic stability.
| Synthetic Option | Advantages | Disadvantages |
|---|---|---|
| Poly Ester or Diester (Group V) | Highest VI, Lowest Pour Point, Highest Thermal Stability | May not be suitable where moisture accumulation is a problem. May not bear API service classification marks. |
| PAO (Group IV) | Excellent VI, Excellent Pour Point, Excellent Thermal Stability | May cause leakage in some instances. Additive stability in cold temperatures for extended periods of time may be a problem. |
Information from How to Select a Motor Oil and Filter for Your Car or Truck, 2nd Edition, by James C. Fitch
6. When Synthetics Always Makes Sense
Extreme conditions and worst-case scenarios demand the use of synthetics. Since they are more expensive, ensure you get value and performance in return. Here are passenger car applications ideally suited for synthetics motor oils:
- High-performance engines: Many high-end sports cars and SUVs benefit from synthetic oil due to high investment and expectations for engine performance and reliability.
- High-performance driving: Motor sports enthusiasts benefit from synthetic oil’s competitive edge, providing power, endurance, and engine reliability.
- Luxury car engines: High-end luxury sedans are best paired with synthetic oil to maintain their performance and longevity.
- Extreme cold starts: Certain synthetics handle cold starts without cranking or oil pressure problems at temperatures as low as -40°C (-40°F).
- Extended drains: If your car, driving habits, and climate conditions align for extended oil drains, synthetics offer the best shot and a safety margin.
- Towing and high loads: Slow speed, high load (e.g., towing), long hills, high-mileage engine, long oil service-interval, and high ambient temperatures create worst-case scenarios best handled by premium synthetics.
- Long engine life: Auto enthusiasts aiming to maximize their car’s lifespan often opt for synthetic oil to ensure the engine’s longevity.
6.1. Unclear Cases for Synthetics
In some instances, the decision to use synthetic motor oil is less clear. Use good judgment and carefully consider all facts and circumstances. For example, the value of synthetic oils in improving fuel economy is still debated, and some evidence suggests the opposite may be true.
7. FAQs About Synthetic Oil
| Question | Answer |
|---|---|
| What exactly is synthetic oil? | Synthetic oil is a lubricant composed of artificially created chemical compounds, engineered by breaking down and rebuilding petroleum molecules for enhanced performance and protection compared to conventional oil. |
| How does synthetic oil differ from conventional oil? | Synthetic oil has a more uniform molecular structure, offering better resistance to chemical degradation, higher viscosity index, improved low-temperature performance, lower volatility, and a longer lifespan compared to conventional oil. |
| What are the main advantages of using synthetic oil? | Key advantages include superior resistance to oxidation and chemical degradation, better performance in extreme temperatures, improved flow at cold temperatures, reduced sludge and deposits, longer oil change intervals, and a more robust film thickness for enhanced protection. |
| Are there any disadvantages to using synthetic oil? | Disadvantages include a higher cost compared to conventional oil, potential for additive precipitation/separation during cold storage, and a possibility of slightly lower fuel economy at highway speeds. |
| Is synthetic oil worth the extra cost? | Synthetic oil can be worth the cost, especially for long-term engine protection and performance. While it is more expensive upfront, it can lead to long-term savings through extended oil change intervals and improved engine component protection. |
| When should I always use synthetic oil? | Synthetic oil is highly recommended for high-performance engines, high-performance driving, luxury car engines, extreme cold starts, extended drain intervals, towing and high load applications, and for those aiming to maximize engine life. |
| How often should I change synthetic oil? | Most brands recommend changing synthetic oil every 5,000 to 7,000 miles, with some brands touting intervals of 15,000 to 25,000 miles. Always refer to your vehicle’s manufacturer recommendations for specific oil change intervals. |
| What is the role of additives in synthetic oil? | Additives play a crucial role in enhancing synthetic oil’s performance. They help prevent degradation, maintain viscosity, protect against wear, and provide various other benefits to ensure optimal engine protection and longevity. |
| Can I mix synthetic oil with conventional oil? | While mixing synthetic and conventional oil is possible, it is generally not recommended as it dilutes the benefits of synthetic oil. For best results, it is advisable to use synthetic oil exclusively. |
| What are PAOs and Esters in synthetic oil? | PAOs (Polyalphaolefins) and Esters are synthetic base oils. PAOs are common due to their balance of price and performance, while Esters offer exceptional thermal stability and low pour point characteristics. Both play vital roles in enhancing the overall performance and protection provided by synthetic oil. |
| How does driving style affect the choice of oil? | Aggressive driving styles often benefit more from synthetic oil due to its superior protection against heat and wear. |
| Can synthetic oil improve fuel efficiency? | The impact of synthetic oil on fuel efficiency is debated, but some evidence suggests it can lead to a slight improvement under certain conditions. |
| Is synthetic oil compatible with older vehicles? | Synthetic oil is generally safe for older vehicles, but it is essential to check manufacturer recommendations. In some cases, synthetic oil’s enhanced cleaning properties may reveal pre-existing issues. |
| Does synthetic oil reduce engine wear? | Yes, synthetic oil typically reduces engine wear due to its more robust film thickness at higher temperatures and loads, offering superior protection to engine components. |
| What environmental benefits does synthetic oil offer? | Synthetic oil can offer environmental benefits through reduced volatility, leading to less oil loss to the exhaust stream and potentially longer oil change intervals, reducing waste. |
| How does synthetic oil perform in extreme temperatures? | Synthetic oil performs exceptionally well in extreme temperatures, maintaining its viscosity and flow properties in both very hot and very cold conditions, providing reliable engine protection in diverse climates. |
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