David S. Wallens
David S. Wallens Editorial Director
5/12/09 12:36 p.m.

Preparing a car for any type of motorsports competition is an exacting exercise. The difference between winning and just running in an event can often be measured in the thousandths of a second, so competitors need to eke every last ounce of performance from their vehicles. That's why even minor ingredients in the performance equation--like different engine lubricants--can be extremely important. An engine that runs too hot will wear more quickly, produce less power, and be more prone to failure. The right lubricant can help keep it cool.

The modern automobile engine has made great developmental strides in the last couple of decades; this has placed new demands on engine lubricants. The oil industry's response has been to develop a new generation of high-quality, high-tech oils based on synthetic base molecules. These new oils last longer, develop more engine power, and are significantly more durable than standard petroleum oils. Many people seem to think that the claims made by these new "wonder oils" are too good to believe, however; this has cast a shadow over the reputation of synthetic oil. Even among motorsports enthusiasts, there is great confusion as to what synthetic oils are, how they are made, and just how they compare to petroleum oils.

In order to learn more about synthetic oils, we traveled to the production facilities of the most respected synthetic oil manufacturers: Red Line Synthetic Oil Corp,, Valvoline, and Bel-Ray Total Performance Lubricants.

Red Line has been in business for quite some time now; and the company's synthetic oils, lubricants, and additives are used by more national racing champions than any other. In fact, at the 1989 SCCA Valvoline Runoffs, more than half of the winning drivers were using Red Line products.

Valvoline is also no stranger to the winner's circle; this company's products have helped to place drivers like Al Unser, Jr., Bobby Rahal, Mark Martin, and Dorsey Schroeder at the top of their fields. Now, after ten years of intensive development, Valvoline is releasing its own line of synthetic motor oils, gear oils and greases.

Bel-Ray has been producing specialty lubricants for more than 40 years. This manufacturer has provided lubricants for NASA's moonwalker, nuclear submarines, tanks, aircraft carrier catapults, and mining equipment weighing 40,000,000 (as in million) pounds. Bel-Ray lubricants are also used heavily in the motorcycle and automotive racing arenas.

Synthetic Oil Construction

Synthetic oils can be derived from several sources, but the most stable are derived from polyol ester bases. These bases are laboratory creations; to make them chemists break apart the molecules that make up a variety substances, like vegetable and animal oils, and then recombine the individual atoms that make up those molecules to make new, synthetic molecules. This process allows the chemists to actually "fine tune" the molecules as they build them. As a result, synthetic molecules are often much more stable--less prone to break apart--than the original molecules. For instance, the molecules of most synthetic oil bases contain no reactive carbon atoms; this is because reactive carbon has a tendency to combine with other elements--like oxygen, to make acids--which makes them unstable, especially at high temperatures. So, in a sense, synthetic oil bases are made up of purpose-built molecules; and like purpose-built race cars, they tend to be streamlined, with no unneeded ingredients or added bulk.

Once the synthetic polyol ester bases are created, anti-wear additives are added. The most common of these are the zinc dithiophosphates, which are essentially combinations of zinc, phosphorus, and sulfur molecules. These combinations are extremely effective as anti-oxidant, anti-wear, anti-corrosion inhibitors. They have good thermal stability, but must be blended in such a way that the ingredients react at the proper temperature.

After that, other additives are added to control rust and foaming, contain foreign particles, etc., until the oil meets the requirements of its intended application.

Each oil manufacturer takes a slightly different approach to producing their synthetic lubricants, but all are guided by the three basic functions of engine lubricants: Friction reduction, heat removal, and containment of contaminants. Let's take a look at how engine oils provide these functions.

Friction Reduction

Friction reduction can be define as the action of maintaining a lubricant between two surfaces that are moving with respect to one another, which avoids a collision of the two surfaces and the resultant damage. The better the lubricant is, the better its friction reduction abilities. Since friction produces heat as well as wear and tear, a good lubricant will reduce overall heat buildup in the engine. This item is especially important, because friction produces a significant portion of the heat generated in the process of operating an engine. Lower operating temperatures will also benefit the lubricant, enabling it to remain more stable and less prone to oxidation. (More on this later in the story.)

Any discussion of a lubricant's friction-reducing properties must also examine its ability to provide Hydrodynamic Lubrication. This condition is present when two interacting metal surfaces are successfully kept apart by a lubricating layer, which eliminates the friction between the surfaces. This can be done mechanically: In the combination of a cylindrical journal and bearing, the rotary shaft acts as a pump which maintains the film of lubricant. The journal floats on a thin film of oil of an equilibrium thickness between the oil input and oil leakage, mostly at the bearing ends. In a situation like this, any friction present is caused by the molecular friction occurring within the lubricant--i.e., its viscosity.

Viscosity can be defined as a fluid's resistance to flowing freely as a result of its internal molecular construction. Viscosity is perhaps the most important property of a lubricant. It controls the formation of lubricating films under both thick and thin film conditions. It affects heat buildup, governs the sealing effect of oils and oil consumption, and significantly affects engine startup at extreme temperatures.

Multi-grade ratings of petroleum oils are made by adding polymeric plastic thickeners to an oil with a very light viscosity. An example of this is 10W-40 oil, which is created by thickening a 10W oil to the equivalent of an SAE 40W oil at 212 degrees F. The reason a 10W oil is used is to maintain low viscosity at low temperatures; this helps with engine startup and cold weather performance. The thickeners increase viscosity at higher temperatures. Unfortunately, when the large molecules of the polymer thickeners encounter a high-stress area, like a bearing, these big molecules tend to align themselves to create a path of least resistance. This greatly reduces the film strength of the oil; the result can be an apparent viscosity that is much lower than the viscosity listed on the container. In fact, a standard 10W-40 oil, when subjected to high stress, may perform to SAE 20 specifications, simply because the added thickeners cannot cope with the additional stress.

Synthetic oils require no thickeners to achieve multi-grade ratings because they are constructed from naturally multi-graded basestocks. In addition, the actual shape of synthetic oil base molecules enables those synthetis to maintain a much higher viscosity under stress. Because of this, most synthetics provide significantly greater viscosity than petroleum oils under high speed conditions.

It is even more important that an oil provide a seal between the piston rings and cylinder walls to ensure maximum compression on the stroke. Most petroleum oils will allow blow-by because their weaker viscosity allows high-pressure gasses to escape into the crankcase area. Modern synthetic oils, on the other hand, prevent blow-by due to better viscosity.

For example, Red Line claims that its 10W-30 Racing Oil will not only outperform 20W-50 petroleum oils, its less dense molecular structure also makes for significantly less viscosity friction within the engine. Bel-Ray has developed a 5/60 weight oil to handle the extreme demands of high-revving motorcycle engines, while Valvoline has concentrated more on automobiles with its 10/30 and 20/50 offerings. In each case, the superior structure of synthetics means better protection. This also help in cold-start situations, where oil circulation is critical.

Read the rest of the story

Teh E36 M3
Teh E36 M3 SuperDork
5/29/09 2:56 p.m.

Another interesting point I've seen made is the question of: How much do you spend on gas for your car? And it lasts how many miles? Essentially for the cost of one tank of gas you get the better protection of synthetic oils. The $20 difference in my opinion is not worth saving.

Also- it would be interesting to have a story on building and breaking in a new engine- would you use synthetics? Is there a particular way to build an engine wherein synthetics would be useful as a first fill? How do the OEM's (Chevy, Porsche, BMW) ship their engines with synthetic new from factory? How long does it take to break in an engine? Does the "motoman" break it in like you drive it theory hold water?

Good story regardless.

Guam135i New Reader
6/20/11 1:55 a.m.

Is this also true for the older car where the machinning tolerances are farther off? Like for example my 1970 Mini which the engine oil also serves as the transmission oil, can I use a synthetic oil?

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