A lubricant is a substance, usually organic, introduced to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, transporting foreign particles, or heating or cooling the surfaces. The property of reducing friction is known as lubricity. A good lubricant generally possesses the following characteristics:
A high boiling point and low freezing point (in order to stay liquid within a wide range of temperature)
A high viscosity index
Thermal stability
Hydraulic stability
Demulsibility
Corrosion prevention
A high resistance to oxidation
Lubricants are generally composed of a majority of base oil plus a variety of additives to impart desirable characteristics. Although generally lubricants are based on one type of base oil, mixtures of the base oils also are used to meet performance requirements.
The term "mineral oil" is used to refer to lubricating base oils derived from crude oil. The American Petroleum Institute (API) designates several types of lubricant base oil:
Group I – Saturates < 90% and/or sulfur> 0.03%, and SAE viscosity index (VI) of 80 to 120 Common are 150SN (solvent neutral), 500SN, and 150BS (brightstock)
Group II – Saturates > 90% and sulfur < 0.03%, and SAE viscosity index of 80 to 120 Have superior anti-oxidation properties since virtually all hydrocarbon molecules are saturated. It has water-white color.
Group III – Saturates > 90%, sulfur < 0.03%, and SAE viscosity index over 120
Group IV 3 b– Polyalphaolefins (PAO)
Group V – All others not included above such as naphthenic, PAG, l 80esters.
The lubricant industry commonly extends this group terminology to include:
Group I+ with a viscosity index of 103–108
Group II+ with a viscosity index of 113–119
Group III+ with a viscosity index of at least 140
Can also be classified into three categories depending on the prevailing compositions:
Paraffinic
Naphthenic
Aromatic
The difference is that synthetic oils are made from more advanced refining processes and are of a higher purity and quality than conventional mineral oils. In contrast, a synthetic lubricant starts circulating faster, protecting moving parts within the engine. Synthetic oils can also significantly improve fuel economy.
Semi synthetic oils are cheaper than fully synthetic as they are a mixture of synthetic and mineral oil. Engines requiring semi synthetic oil must use at least semi synthetic oil (not mineral oil) but may benefit from upgrading to fully synthetic oil for increased protection and performance.
Oils can be separated into multigrade oils and monograde oils. Multigrade oils must fulfill two viscosity specifications, their viscosity grade consists of two numbers, e.g. 10W-40: 10W refers to the low-temperature viscosity ("Winter"), 40 refers to the high-temperature viscosity ("Summer").
Below are some prominent lubricant quality regulations in industry, among many others:
The Society of Automotive Engineers (SAE) grade determines the lubricant’s fluidity at high and low temperatures. It classifies lubricating oils for transmissions and engines on the basis of their viscosity at a reference temperature.
The American Petroleum Institute (API) is an organization that represents the petroleum and natural gas industry. It has established classifications that consist of two letters. The first letter signifies the type of application (“S” for the service classification of gasoline engines or “C” for the commercial classification of diesel engines). The second letter provides the performance level of the lubricant. The API considers all standards preceding SJ and CF as obsolete. The SN standard identifies lubricants that offer enhanced engine protection. These lubricants improve general engine performance and allow extended oil change intervals.
Over time, dirt can cause corrosion and decrease the life of an engine. Routine oil changes are part of engine maintenance to help remove particles and sludge and keep engines at peak condition. It also improves gas mileage. Poor engine lubrication can lead to increased fuel consumption and quick wear and tear of moving parts, so make sure there is enough clean oil in the engine as per the recommended maintenance cycle.
Surfactants also called surface-active agent are compounds that lower the surface tension (or interfacial tension) between two liquids, between a gas and a liquid, or between a liquid and a solid, thereby increasing its spreading and wetting properties. Surfactants may act as detergents, wetting agents, emulsifiers, foaming agents, and dispersants agents. In the dyeing of textiles, surfactants help the dye penetrate the fabric evenly.
Some practical applications and products, includes detergents, fabric softeners, emulsions, soaps, paints, adhesives, inks, anti-fogs, ski waxes, snowboard wax, deinking of recycled papers. In the dyeing of textiles, surfactants help the dye penetrate the fabric evenly.