What Is Oil?

What Is Oil?

Simply put, oil is a chemical compound that is in a liquid state at ambient temperatures and will not mix with water. Oils are derived from crude oil, also called petroleum, which is the product of ancient organic material that has been subjected to heat and pressure within the Earth’s crust.

The viscosity of crude oil can range from relatively fluid to as heavy as molasses. It is distilled by heating into light, intermediate and heavy fractions. The lighter fractions are converted into petrol and diesel. The heavier oils are refined to form clear, bright amber oils, some of which are used to blend engine oils. These are often referred to as API Group I and Group II base oils. Further refining of these oils, by a process called hydrocracking, will produce oils that are nearly colorless and have reduced volatility and improved oxidation resistance. These are referred to as API Group III base oils.

Years ago engines were filled with refined mineral oils called straight oils with nothing added. These early mineral oils deteriorated rapidly, leading to black sludge, corrosion and, before long, a worn-out motor. In the Fifties, lubricant manufacturers discovered how to improve the performance of motor oil by including additives with specific functions such as rust prevention, oxidation resistance, cleaning and anti-wear additives. The use of polymers or Viscosity Index Improvers allowed formulators to tackle the problem of cold starting by creating multi-grade oils. Polymers are long molecules that expand and contract as the oil is heated and cooled. Polymers effectively reduce the rate of viscosity change that the oil undergoes when heated and cooled.

Synthetic oils are man made fluids. Now-a-days, there’s a wide array of synthetic compounds, which are used in various quantities to give oil the desired performance and wear characteristics.

Chemical compounds can be blended to make molecules with desirable lubricating characteristics such as thermal and evaporation resistance. The two key synthetic base fluids in engine oils are PAOs (polyalphaolefins), which replace mineral oils, and esters. Where PAOs act like improved or superior mineral oil base fluids, esters also provide important functions such as improved additive solubility, detergency, lubricity or slipperiness and lubrication.

We all know that oil keeps metal parts moving by making them slippery, thus preventing metal components from making contact with each other. A plain bearing spinning at high speed floats on a film of oil so there is no metal-to metal contact. The high velocity drives oil between the two surfaces, and the oil film supports the load. At lower engine speeds, however, there is inevitably some contact between the bearing shells and crankpins. This is where oil must do its more sophisticated lubricating work. Special compounds in the oil react with metal at high pressure and temperature to provide a very thin protective film, which prevents scoring where metal surfaces come into contact. Finally, the esters used in Bel-Ray’s premium oils are attracted to metal by electrostatic forces and cling on even when surfaces are forced into contact.

Choosing the type of oil that will last longest is not as easy as choosing a synthetic product over a mineral product; the oil must be shear-stable. Bel-Ray offers a range of very high specification shear-stable motorcycle oils. The shear-stable part means the oil contains a high quality multi-grade polymer, which is more important than an unspecified synthetic claim. In fact, a shear-stable mineral oil is a better choice than a synthetic of dubious stability.

There are many oil additives on the market which claim to offer improved performance, but do they work? The simple answer is “no”!

Bel-Ray put vast amounts of money and research into obtaining optimum lubrication and if magical additives existed, then Bel-Ray would be using them already. Some additives actually contain substances, such as chlorine-based chemicals, that corrode engine internals, and additives containing PTFE do very little except clog the oil filter.