Why synthetic motor oil?
Modern Engines Prefer Synthetic Motor Oils
Synthetic Motor Oil
All around the world, other than in Germany, Group III and Group IV motor oils are both labelled as Synthetic Motor Oils. This is not allowed in Germany. In fact, according to German Law, German Motor Oils have to clearly differentiate between the two.
Group III is made by taking mineral oil and then subjecting it to extremely high temperatures and pressure and “Cracking” the long molecules with hydrogen, thus these oils are also called Hydrocracked Oils or H.C. Oils. Group IV Oils are made from Gasoline and are therefore very expensive. Group IV Oils are also known as Polyalphaolefins or PAOs. Both oils have short molecules that are excellent against aging, evaporation loss and cold starting. We can see why the rest of the world calls the both HC Synthesis and PAOs Synthetic.
Auto manufacturers have taken advantage of the properties of synthetic motor oils and specify them for new engines. These engines, manufactured to tighter tolerances with direct fuel injection, variable valve timing, and turbo charging, produce more horse power yet use less fuel and produce fewer emissions.
Types of Synthetic Oil
Group III base oil is high-quality mineral oil that has gone through a process called severe hydrocracking. This process takes place at 650 °F and 1,000 psi where the different hydrocarbon molecules are broken into shorter uniform sized molecules. Impurities such as sulphur and nitrogen are removed. Waxy compounds are subsequently removed by catalytic dewaxing and wax hydroisomerization. The resulting oil is chemically modified Group III mineral base oil.
Group IV oil is a group of chemically synthesized products called polyalphaolefins (PAO) that are manufactured from ethylene. Lubrication oils made from Group III and Group IV base oil stock have similar properties and outperform conventional mineral oils.
There is another base oil group, Group V, which includes specialty synthetic oils that are used as oil additives and for other specialized applications.
In Europe, oil manufactured from chemically modified Group III base oil is called HC synthesis or synthetic technology oil and that from Group IV base oil is known as fully synthetic oil. In North America, all oil manufactured from Group III and Group IV base oil is called fully synthetic oil. In practical terms, there is little difference in the technical characteristics of synthetic oil manufactured from Group III and Group IV base oil stocks.
Semi-synthetic oil is oil that is a blend between no more than 30 per cent synthetic oil and mineral oil; it is better than mineral oil but inferior to fully synthetic oil.
Manufacture of Synthetic Motor Oil
The starting point is the selection of high quality base oils that meet certain requirements such as viscosity, purity, and consistency. A number of additives may be required, including:
• Wear resistance additives
• Friction modifiers
• Anti-foaming additives
• Corrosion inhibitors
• Viscosity index improvers
The base oils are blended to produce the required oil characteristics, and small quantities of additives are added to the base oil. Cleanliness is essential to avoid contamination. Each oil is formulated in a very specific way to meet the required specifications.
Technical Characteristics of Synthetic Oil vs. Mineral Oil
• Oil viscosity: This is the most important characteristic and is a measure of the thickness the oil is at different temperatures. High viscosity oils are thicker than low viscosity oils. Modern oils are usually multigrade oils, which remain thin enough to lubricate engines at very cold temperatures. It is important to use the motor manufacturer’s recommended grade of oil.
• Viscosity index: When oil gets colder, it becomes thicker, and when it gets hot, it thins. The viscosity index is a measure of the change in oil viscosity between 100 °F and 210 °F. Oil with a high viscosity index has a lower change in viscosity than one with a low viscosity index. Group I and II mineral oils have a viscosity index below 120 and need viscosity improvers to raise their viscosity to usable levels. Synthetic oils have viscosity indexes approaching 180 that are often achieved without the use of additives.
• Pour point: This is the lowest temperature at which oil can be poured out of a container. It’s a good measure of the oil’s suitability for cold weather; synthetic oils reach much lower pour points than mineral oils.
• Total base number: This measures the ability of the oil to absorb acid produced in an engine. The higher the number, the longer oil will last.
Although it is possible to formulate mineral oils that have characteristics approaching those of synthetic oils, these oils require additive packs that wear out and this limits the usable service life of mineral oils.
Oil Specifications: How to Select the Right Oil
• API gasoline engine oil rating: If an API rating is specified, the oil should meet or exceed the rating. The API rating for gasoline engine oil has two alphabetical letters; the lowest is SA and the highest, introduced in 2010, is SN.
• API diesel engine oil rating: The lowest rating is CA and the highest for 2010 vehicles is CJ-4. These requirements are backwardly compatible.
• ACEA rating for European vehicles: European manufacturers use a different system, and oil selected should meet the specific requirements for a particular vehicle. The common categories are A1/B1, A3/B3, A3/B4 and A5/B5. The A refers to gasoline vehicles and the B to diesel vehicles. Oil that does not meet the correct specification should not be used.
• Manufacturers’ specifications: In some cases, the handbook will include a statement that the oil should meet a particular manufacturer’s specification; this especially applies to European sourced turbocharged and direct-injection engines.
Practical Applications for Synthetic Oil
Synthetic oil is superior engine oil that can be interchangeably used with normal mineral motor oil. Its high qualities mean that it outlasts mineral oil while providing better engine protection. Motor manufacturers have taken advantage of these properties and specify synthetic motor oil for many modern vehicles, especially those with extended oil change intervals. The use of mineral oil effects to higher oil consumption and to shorten oil change intervals. Synthetic oil can be safely used in older cars provided it meets or exceeds manufacturers’ original specifications. It will not damage the engine, but the cleaning and desludging properties of synthetic oil may loosen deposits in worn engines and increase oil consumption.
Benefits of Synthetic Motor Oils
Specific benefits of synthetic oils include:
• High viscosity index: The high viscosity index of synthetic oils means they retain lubricating and other engine protection properties at high and low temperatures, thus providing better cold start protection in winter as well maintaining adequate engine lubrication in hot summer weather.
• Long engine life: The improved lubrication properties means that engines last longer with less wear
• Fewer oil changes: Engines running synthetic oil need fewer oil changes; some European vehicle manufacturers using synthetic oil recommend oil change intervals that exceed 18,000 miles. Synthetic oils do not oxidize, break down, or form sludge as quickly as mineral oils.
• Improved fuel economy and power: The lower friction properties of synthetic oils means that fuel economy and engine power is slightly improved.
• Improved high temperature protection: Synthetic oils are resistant to breakdown in hot spot areas on turbocharged vehicles.
Synthetic Oil’s Future
The use of synthetic motor oil is growing rapidly as auto makers respond to the demand for smaller yet more powerful engines that use less fuel and produce lower emissions. These new engines are built to tighter tolerances and have lubrication requirements that can only be met by high quality synthetic motor oils.
Although synthetic motor oils are more expensive than mineral oils, they outperform mineral motor oils, resulting in longer lasting and better performing engines in new and used cars, trucks, and vans.