Racing Fuel & Oil

Racing Fuel & Oil

Properties of Motor Oil

By Phil White

Most motor oils are made from a heavier, thicker petroleum hydrocarbon base stock derived from crude oil, with additives added as needed to improve the properties. One of the most important properties of motor oil in maintaining a lubricating film between moving parts is its viscosity. In layman's terms, the viscosity of a liquid can be thought of as its "thickness" or a quantity of resistance to flow. The viscosity must be high enough to maintain a satisfactory lubricating film, but low enough that the oil can flow around the engine parts satisfactorily to keep them well coated under all conditions. The viscosity index is a measure of how much the oil's viscosity changes as temperature changes. A higher viscosity index indicates the viscosity changes less with temperature than a lower viscosity index.

Another important property of motor oil is its pour point, which is indicative of the lowest temperature at which the oil could still be poured satisfactorily. The lower the pour point temperature of the oil, the more desirable the oil is when starting up at cold temperature.

Oil is largely composed of hydrocarbons, which can burn if ignited. Still another important property of motor oil is its flash point; the lowest temperature at which the oil gives off vapors which can ignite. It is, of course, dangerous for the oil to ignite and burn, so a high flash point is desirable. At a petroleum refinery, fractional distillation to separate crude oil fractions removes the volatile components, which more easily ignite, from the motor oil fraction; therefore, increasing the oil's flash point.

Another test done on oil is Total Base Number (TBN), which is a measurement of reserve alkalinity of an oil for neutralizing acids. The resulting quantity is determined as mg KOH/(gram of lubricant). Analogously, Total Acid Number (TAN) is the measurement of a lubricant’s acidity content. Other tests include zinc, phosphorus, or sulfur content, and testing for excessive foaming.

Most commercial oils have a minimal amount of zinc dialkyldithiophosphate as an anti-wear additive to protect contacting metal surfaces with zinc in case of metal to metal contact.

Motor Oil Viscosity and Horsepower

Using a high-viscosity motor oil could reduce your engine horsepower. It takes horsepower to push thick high-viscosity oil through the engine oil passages. Here's an example, you could lose 10 or more horsepower @ 5500 RPM in a Chevy 350 cid engine just by using a high-viscosity motor oil over a standard viscosity motor oil. In some cases your engine will not be any better protected using a high-viscosity motor oil over a lower-viscosity motor oil. Contact your favorite racing motor oil company for more information. Always follow your vehicle manufacturers motor oil recommendations.

Methanol Racing Fuel Basics

Methanol, also known as methyl alcohol or wood alcohol, is a chemical compound with chemical formula CH₃OH. It is the simplest alcohol, and is a light, volatile, colorless, flammable, poisonous liquid that is used as an antifreeze, solvent, fuel, and as a denaturant for ethyl alcohol.

Methanol is produced naturally in the anaerobic metabolism of many varieties of bacteria. As a result, there is a small fraction of methanol vapor in the atmosphere. Over the course of several days, atmospheric methanol is oxidized by oxygen by the help of sunlight to carbon dioxide and water.

Methanol burns in air forming carbon dioxide and water:

2CH₃OH + 3 O₂ --> 2CO₂ + 4H₂O

A methanol flame is almost colorless. Care should be exercised around burning methanol to avoid being burned.

Drag Tech Fact: Propylene oxide is a highly toxic flammable chemical compound. It was once used as a racing fuel, but that usage is now prohibited under NHRA rules for safety reasons.