Synthetic oil has become a prominent term in automotive maintenance, often touted for its superior performance compared to conventional oil. But What Is Synthetic Oil exactly, and why is it gaining so much popularity among car owners and manufacturers alike? This comprehensive guide, crafted by auto repair experts at cardiagxpert.com, delves into the essence of synthetic oil, exploring its composition, advantages, disadvantages, and when it truly makes a difference for your vehicle.
_extra_large.jpeg)
Close-up view of a bottle of synthetic motor oil, highlighting its advanced formulation for engine lubrication and protection.
Synthetic Oil Explained: Composition and Manufacturing Process
At its core, synthetic oil is a lubricant engineered from artificially created chemical compounds. Unlike conventional mineral oil, which is refined directly from crude oil, synthetic oil undergoes a more complex process. It starts with breaking down petroleum molecules and then rebuilding them to create a lubricant with enhanced properties.
Imagine examining a drop of oil under a powerful microscope. Conventional oil, derived from refined crude oil, would reveal a chaotic mix of molecules in various shapes, sizes, and structures. In contrast, a drop of synthetic oil would present a much more uniform picture – millions of molecules, nearly identical in size and structure. This uniformity is the key to synthetic oil’s superior performance characteristics.
Full synthetic oils are crafted using a completely synthetic base stock, designed molecule by molecule without relying on petroleum. They are further enhanced with additives to combat oil degradation and improve engine protection. Synthetic blends, on the other hand, are a combination of conventional mineral oil and synthetic base stocks. While offering some benefits over purely conventional oil, they don’t provide the full advantages of a complete synthetic formulation.
While various types of synthetic oils exist, each with unique properties and applications, polyalphaolefins (PAOs) are the most common in automotive service. For simplicity, this article will primarily focus on PAOs when discussing synthetic oils.
Synthetic vs. Conventional Oil: Unpacking the Differences
Most modern vehicles are designed to function with either synthetic or conventional oil as long as they meet the specifications set by organizations like the American Petroleum Institute (API) and the International Lubricant Standardization and Advisory Committee (ILSAC). However, the automotive industry widely promotes synthetic oils for their superior performance compared to their conventional counterparts.
_extra_large.jpeg)
Microscopic comparison illustrating the uniform molecular structure of synthetic oil versus the varied structure of conventional oil, emphasizing the consistency and engineered nature of synthetic lubricants.
Numerous studies have rigorously compared synthetic oil to conventional mineral oil over the years. Notably, the American Automobile Association (AAA) conducted tests in certified labs, utilizing American Society for Testing and Materials (ASTM) standardized methods. These tests aimed to quantify the performance differences between oils marketed as conventional and those marketed as full synthetic.
The AAA study revealed that, on average, synthetic oils outperformed conventional oils by an impressive 47 percent across various tests. These tests assessed crucial properties such as shear stability (resistance to viscosity loss under stress), deposit formation (sludge and varnish buildup), volatility (tendency to evaporate), cold-temperature pumpability (flow in freezing conditions), oxidation resistance (resistance to breakdown from oxygen), and oxidation-induced rheological changes (viscosity changes due to oxidation).
The automotive landscape is shifting towards synthetic oil. Consumer Reports indicates that nearly 70 percent of new cars in the 2019 model year were filled with either full synthetic or synthetic blend oil. This trend underscores the growing recognition of synthetic oil’s benefits. Despite this shift, it remains critical for vehicle owners to adhere to manufacturer recommendations regarding oil type and change intervals. Michael Calkins, Technical Services Manager for AAA, emphasizes, “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.”
While conventional oil provides adequate engine lubrication in many situations, it has inherent limitations. These can include reduced fluidity at extremely low temperatures, lower thermal and oxidative stability (chemical breakdown at high temperatures), and less robust viscosity protection against wear and friction under heavy engine loads and high temperatures. The advancements in synthetic oil technology have brought these limitations of conventional oil into sharper focus.
Advantages and Disadvantages of Synthetic Oil: Weighing the Pros and Cons
Switching to synthetic motor oil offers several notable advantages over conventional options. However, it’s essential to consider both the pros and cons to make an informed decision for your vehicle.
Here are some key advantages that synthetic oils (specifically PAOs) generally offer over conventional engine oils. It’s important to note that this comparison assumes similar additive packages, which is rarely the case. Synthetic oil formulations often include superior additive packages, making the overall performance difference even more pronounced. Therefore, the enhanced performance might stem from the synthetic base oil itself, the advanced additives, or a combination of both.
-
Superior Resistance to Degradation: Conventional mineral oils are more susceptible to chemical degradation (oxidation) when exposed to harsh engine conditions. These conditions include combustion byproducts, fuel and water contamination, metal particles, acids, and extreme heat. Oil degradation leads to sludge, varnish, deposits, corrosion, viscosity changes, and impaired engine performance. Synthetic oils exhibit significantly better resistance to these factors.
-
Naturally Higher Viscosity Index: Synthetic oils have a naturally higher viscosity index, meaning their viscosity remains more stable across temperature fluctuations. Viscosity is crucial for maintaining an oil film between moving engine parts, preventing friction and wear. Synthetic oil ensures consistent protection during engine start-up and operation across a wider temperature range.
-
Enhanced Cold-Temperature Performance: At extremely low temperatures, conventional oils can thicken excessively, hindering pumpability and circulation. This can lead to lubricant starvation and engine damage, especially during cold starts. Synthetic oils maintain better fluidity at low temperatures, ensuring rapid lubrication even in freezing conditions.
-
Lower Volatility: Synthetic engine oils are generally less volatile than mineral oils. This means less oil evaporates and escapes through the engine’s exhaust, reducing atmospheric pollution and potentially decreasing the need for oil top-ups between changes.
-
Extended Lifespan and Oil Change Intervals: Perhaps the most significant advantage, and a major reason for synthetic oil’s popularity, is its extended lifespan. While conventional oil changes are typically recommended every 3,000 to 5,000 miles, synthetic oil change intervals can range from 5,000 to 7,000 miles, with some brands claiming much longer intervals (15,000 to 25,000 miles). This extended lifespan is primarily due to synthetic oil’s superior resistance to degradation. Regardless of oil type, always adhere to your vehicle manufacturer’s recommended oil change intervals.
Despite these compelling advantages, synthetic oil also has a few disadvantages:
-
Higher Cost: The most significant drawback is the price. Synthetic oil typically costs two to four times more than conventional oil. This upfront cost is a primary consideration for many car owners.
-
Potential Additive Precipitation: In cold storage conditions, synthetic oils might be more prone to additive precipitation. This can cause certain additives to separate from the oil, potentially compromising their effectiveness.
-
Slightly Reduced Fuel Economy at Highway Speeds: Multi-grade synthetic motor oils might exhibit marginally lower fuel economy at highway speeds compared to mineral oils. This is attributed to mineral oils requiring more viscosity index improvers, an additive that can reduce viscosity friction through shear-induced temporary viscosity thinning.
| Advantages and Disadvantages of Synthetic Oil |
|---|
| Advantages |
| Resistant to oxidation and chemical degradation |
| Withstands temperature extremes better (cold and hot) |
| Flows better at cold temperatures |
| May produce less sludge and surface deposits |
| Longer oil change intervals |
| More robust film thickness at higher temperature and higher loads |
Is Synthetic Oil Worth the Cost? Evaluating the Value Proposition
Deciding whether to use synthetic oil often boils down to cost versus benefit. The price difference between synthetic and conventional oil is undeniable, but the long-term value of synthetic oil can be compelling.
“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 AAA’s Michael Calkins.
In 2019, a survey of AAA-approved auto repair facilities indicated that five quarts of conventional oil cost approximately $28, and a conventional oil change averaged around $38. In contrast, five quarts of full synthetic oil cost about $45, and a full synthetic oil change averaged $70. Switching to synthetic oil could increase your annual oil maintenance cost by approximately $64, or about $5.33 per month.
_extra_large.jpeg)
A visual cost breakdown comparing the price of conventional versus synthetic oil changes, highlighting the slightly higher upfront expense of synthetic oil but suggesting potential long-term value.
While manufacturer-approved conventional oil won’t inherently harm your engine, investing the extra $5 per month for synthetic oil can provide long-term engine protection. This protection can potentially save you money down the line by extending the lifespan of engine components and reducing the risk of costly repairs. Furthermore, the extended oil change intervals of synthetic oil can offset some of the higher upfront cost.
When considering oil change frequency, synthetic oils generally allow for longer intervals, typically between 5,000 to 7,000 miles, and in some cases, up to 25,000 miles depending on the brand. Conventional oil changes are usually recommended every 3,000 to 5,000 miles. If opting for extended intervals with synthetic oil, it’s crucial to upgrade to a high-quality oil filter designed for extended service life to match the oil’s performance.
So, is synthetic oil truly better for your engine? “In general, yes – provided the automaker’s viscosity grade and other oil requirements are adhered to,” confirms Calkins. While mineral oil provides adequate lubrication, synthetic oil offers enhanced engine protection through its higher-quality, more refined base oils.
“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.
Consider your vehicle ownership timeline. If you plan to keep your car for an extended period, the investment in premium lubrication like synthetic oil may contribute to a longer engine life. However, if you typically trade in your vehicle relatively quickly, the long-term benefits of synthetic oil might accrue more to the next owner.
Exceptions exist. Engines subjected to extreme operating conditions or “worst-case scenarios” can significantly benefit from synthetic oil even in the short term. These scenarios include extreme temperatures, neglected oil changes, heavy loads, frequent cold starts, short commutes, and impaired engine cooling.
Synthetic Engine Oils: A Deeper Look at Base Oil Types
Synthetic oil production starts with base oils or base stock oils. The American Petroleum Institute (API) classifies base oils into five groups. Groups I, II, and III are refined from petroleum crude oil. Group IV base oils are fully synthetic, and Group V encompasses all base oils not included in the first four groups. Two of the most common base oils used for synthetic oil are Polyalphaolefins (PAOs) and Esters (Diester and Polyol).
-
PAOs (Polyalphaolefins): These Group IV base oils are the most prevalent in synthetic oil production due to their balanced performance and cost-effectiveness. PAOs share a similar chemical composition to mineral oil but are manufactured rather than extracted, resulting in a purer, more consistent product. PAOs offer several advantages, including superior oxidation and thermal stability, low volatility, excellent heat dissipation, a low pour point, and the absence of waxy molecules.
-
Esters (Diesters and Polyol Esters): These Group V base oils are created through a chemical reaction between acids and alcohols, releasing water molecules in the process. Diesters and polyol esters are the most common esters used in synthetic motor oil. Diesters are often used as additives in PAO-based synthetic oils. Esters are characterized by high thermal stability and excellent low-temperature flow properties but may exhibit poor hydrolytic stability (resistance to degradation in the presence of water).
| 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
When Synthetics Always Make Sense: Ideal Applications
In demanding conditions and “worst-case scenarios,” synthetic oil becomes a clear choice. Given its higher cost, maximizing its value and performance is essential. Here are passenger car applications where synthetic motor oils are ideally suited:
-
High-Performance Engines: High-end sports cars and performance SUVs, with their significant investment and expectations for engine power and reliability, are prime candidates for synthetic oil.
-
High-Performance Driving: Motor sports enthusiasts seeking a competitive edge in power, endurance, and engine reliability will benefit from the enhanced performance of synthetic oil.
-
Luxury Car Engines: Luxury sedans, often representing a substantial investment, are best paired with synthetic oil to ensure optimal engine protection and longevity.
-
Extreme Cold Starts: Certain synthetic oils are engineered to handle cold starts flawlessly, even at temperatures as low as -40°C (-40°F), eliminating cranking issues and ensuring immediate oil pressure.
-
Extended Oil Drains: For drivers who have carefully evaluated their driving habits, vehicle, and climate and determined they are suitable for extended oil change intervals, synthetic oils offer the best performance and a greater safety margin.
-
Towing and High Loads: Demanding conditions like slow speeds, heavy loads (towing), steep inclines, high-mileage engines, extended oil service intervals, and high ambient temperatures create extreme stress on engine oil. Synthetic oils with premium additive packages can mitigate wear and provide superior protection in these scenarios.
-
Long Engine Life Expectancy: Car owners aiming to maximize the lifespan of their vehicles and achieve high mileage will find synthetic oil a valuable investment in long-term engine durability.
In some situations, the decision to use synthetic motor oil is less clear-cut. In these instances, careful consideration of your specific circumstances and vehicle needs is crucial. For example, the fuel economy benefits of synthetic oil remain debated, and in some cases, conventional oil might offer comparable or even slightly better fuel efficiency in certain driving conditions.
Ultimately, understanding what synthetic oil is and its properties, advantages, and disadvantages empowers you to make an informed decision about the best engine lubrication for your vehicle. Always prioritize your manufacturer’s recommendations and consider your driving habits and vehicle usage to determine if the benefits of synthetic oil outweigh the increased cost for your specific needs.
