Glossary

Many of these terms are terms used in the field of tribology and engineering, however there are a few that are my own inventions. These terms just make it simple for me to convey an idea without having to explain it every time. Study hard, because there will be a quiz at the end.

 

2T –

  • An abbreviation or alternative wording for 2-stroke and 2-cycle. The “T” may stand for either the German word takt or the French word temps, which both have a general translation to time; as in 2-time in reference to the engine cycles of a 2-stroke motor.

4T –

  • An abbreviation or alternative wording for 4-stroke and 4-cycle. The “T” may stand for either the German word takt or the French word temps, which both have a general translation to time; as in 4-time in reference to the engine cycles of a 4-stroke motor.

Acid Number –

  • A measurement of the acidity of a fluid. This number is often used in used oil analysis (UOA) to determine oil degradation. In order to use the acid number in UOA’s however a starting acid number acquired from a virgin oil sample is required to accurately identify the oil’s condition.

American Petroleum Institute (API) –

  • A professional organization that sets the regulations and specifications for the performance levels of gasoline and diesel engine oils. They also specify the performance criteria for the various types of gear oils.

Antioxidant –

  • A category of additive utilized to retard oxidation and neutralize acids.

Antiwear –

  • A category of additive utilized to reduce the wear on lubricated parts.

ASTM Method –

  • A standardized testing method specified by the American Society of Testing and Materials (ASTM). All ASTM testing methods can be found in the ASTM publication for test methods or can be purchased online individually. For almost all lubricants, the ASTM method number is preceded by the letter D.

Base Number –

  • A measurement of the alkalinity of a fluid. This number is often used in used oil analysis (UOA) to determine oil degradation. In order to use the base number in UOA’s however a starting base number acquired from a virgin oil sample is required to accurately identify the oil’s condition.

Base Oil/Base Fluid –

  • Lubricating oil used as the foundation for finished lubricants. Base oils can consist of oils refined from petroleum crude oil or synthetically derived oils and are categorized into five main groups.

Belt Drive –

  • A type of final drive that uses a set of pulleys and a flexible belt to rotate the rear wheel.

Boundary Lubrication –

  • The type of lubrication where there is no fluid between two surfaces and they come in direct contact with one another

Chain Drive –

  • A type of final drive component that uses a set of sprockets and a roller chain to rotate the rear wheel.

Cold Crank Simulator (CCS)

  • A Testing apparatus used to determine a fluid’s high shear rate viscosity at low temperatures in order to evaluate its resistance to moving parts traveling through it.

Defoamer –

  • A category of additive utilized to reduce or eliminate the tendency for oils to foam as air is introduced.

Detergency –

  • The tendency for an oil to clean deposits and resist the formation of deposits by the actions of carbon solubility. Detergency can be a function of base fluid and additives.

Dispersant –

  • A category of additive utilized to maintain the physical suspension of contaminants in oil so as to transport them through the oil filter.

Drain Interval –

  • The miles travelled of hours of running time a machine has had since the oil was last changed. On-road and dualsport riders commonly change the oil according to the miles travelled. Racing and motocross riders often change the oil according to the amount of time the engine has been running.

Dry Clutch –

  • A clutch that operates without fluid lubrication and relies on air circulation for cooling.

Dynamic Friction Index (DFI) –

  • A test result that is part of the JASO 4-stroke motorcycle engine oil specification to classify an oil’s wet clutch frictional performance. The DFI is comparable to clutch friction after the clutch is engaged when the engine and transmission are already spinning separately.

Dynamic Viscosity –

  • A measurement of a fluids resistance to objects passing through it. This is sometimes referred to as high shear viscosity.

Economy of Scale* –

  • The principle that the more volume of a material a company can buy at once, the cheaper the overall price of that material is. This plays out in the lubricant market in a simple way. A Large, international company can buy base oils and additives in much larger quantities than a small regional or niche lubricant manufacturer can. So if these two companies made an identical product, the overall cost of that product would be less for the large company than it would be for the smaller company.

 

*The concept of economy of scale is much more complicated than I have defined it above and there are many more overhead costs overlooked in that example, but that is the basic gist of the idea.

Elastohydrodynamic Lubrication –

  • The type of lubrication where a fluid film does exist between two surfaces but those surfaces are under enough load to deform at the nearest contact points.

Ester  –

  • In regards to lubricants, esters are a type of base oil found in the group V category. They are generally synthetic but can be biobased as well. There are many different types of esters and each type has its own unique properties that make them useful in different applications.

Extreme Pressure or EP –

  • A category of additive utilized to protect surfaces from damage from high loads by preventing boundary lubrication from occurring.

Finished Lube –

  • A completely blended product sold to customers.

Flash Point

  • A way to measure flammability characteristics of a fluid. It is measured by determining the temperature at which the oil vaporizes rapidly enough to make the volume of air directly above the liquid flammable.

Foaming Tendency –

  • A test used to measure an oil’s ability to resist foam formation and persistence on its surface. The test is typically performed in three distinct sequences. The first is at room temperature (24°C or 75°F), the second is at 93°C (200°F) and the third is the same sample from condition two after it is cooled back to room temperature. The results are recorded as two volumes of foam in mL. The first volume is recorded immediately after five minutes of air bubbling into the oil is complete and the second volume is recorded after 10 minutes of let down time has passed.

Friction Modifier –

  • A category of additive utilized to alter the natural friction characteristics of and oil formula.

Functional Group –

  • A section of a molecule which is attached to the main structure of the molecule that has a specific purpose. Functional groups are reactive portions of a particular chemistry that give it specific properties that depend on the chemistry of that group. Functionalize is the act of adding a functional group to a molecule and molecules with function groups attached are referred to as functionalized.

Grease –

  • A solid or semi-solid type of lubricant.

 Grease Penetration –

  • A measurement of the hardness or softness of grease. This measurement is the depth at which a weighted cone will penetrate into the surface of a specific volume of grease and it is represented in decimillimeters (1/10 of 1 millimeter).

High Temperature, High Shear Rate Viscosity (HTHS) –

  • A test used to determine a fluid’s high shear rate viscosity at high temperatures in order to evaluate its resistance to moving parts traveling through it.

Hydrodynamic Lubrication –

  • The type of lubrication where a full fluid film exists between two surfaces and no physical contact is made between the surfaces.

Infrared Absorption Spectrum Analysis (IR Scan) –

  • A type of scan that identifies chemical bonds and limited chemical structure of a material. This test is used as a sort of chemical fingerprint of an oil so it can be identified by the particular peaks and valleys at specific wavelengths.

International Standards Organization (ISO) –

  • An organizing body that oversees many testing protocols and countless standards around the world. In particular, ISO regulates the ISO 2-stroke engine oil L-EG standards (ISO 13738 specification)

JALOS –

  • Japanese Automotive Lubricating Oil Society. JALOS oversees the implementation of the JASO clutch performance specifications.

JAMA –

  • Japanese automotive manufacturer association. A working group made up of representatives from Honda, Yamaha, Kawasaki and Suzuki for the purpose of developing motorcycle standards.

JASO –

  • JASO registrations are a set of performance specifications set by JALOS to set standard performance requirements for motorcycle engine oils. The registrations are broken down into four possible criteria. MB is for friction modified engine oils for use in engines without an integrated wet clutch. MA is a broad category of wet clutch compatible specifications with two more specific subsections of MA1 and MA2.

Kinematic Viscosity –

  • A measurement of a fluids ability to flow. The more viscous oil is, the thicker it is. This is sometimes referred to as low shear viscosity.

Lubricant Marketer –

  • A company or organization that actively sells lubricants. This may be a manufacturer or a distribution company or any other organization that sells a specific brand name product.

Lubricity –

  • A characteristic of lubricants that describes the ability to reduce friction.

Mixed Film Lubrication –

  • The type of lubrication where a mixture of hydrodynamic and boundary conditions exist at the same time.

Molybdenum –

  • A lubricant additive used for extreme pressure protection and anti-frictional properties. Solid molybdenum disulfide is common in grease and sometimes suspended in oil, whereas molybdenum dithiocarbamate (MoDTC) is common in energy conserving or friction modified oils.

Naphthenic oil –

  • A type of group V base oil refined from naphthenic crude oil.

National Lubricating Grease Institute (NLGI) –

  • A professional society whose purpose is the research and advancement of grease technology.

OEM or Original Equipment Manufacturer –

  • OEMs are the machine manufacturers or part manufacturers. In the world of motorcycles these are your motorcycle manufacturers and aftermarket part companies.

Oil Refining –

  • The process of taking crude oil mixtures and extracting the various compounds found in those mixtures to isolate specific chemistries for specific uses. The refining process of crude oil typically yields gasoline, kerosene, asphalt, diesel fuel, fuel oil, various gases, other small residuals and finally lubricating base oils. Gasoline makes up almost 50% of the volume of crude oil whereas lubricating base oils make up about 1.2% of the total volume in crude oils.

Oxidation –

  • A chemical reaction where an oxygen atom bonds to an existing molecule. When referring to engine oil, oxidation is one of the major contributors to the overall breakdown and the need to change the oil. Oxidation leads to acid formation and other harmful by-products in the oil requiring the oil to be changed.

PAO –

  • Polyalphaolefin is a type of base fluid categorized as a group IV base fluid. PAOs all have the same basic chemical structure with the exception of carbon chain length. For instance low viscosity PAO oil will have short molecular chains and high viscosity PAO will have long molecular chains.

Paraffinic oil –

  • A type of base oil refined from paraffinic crude oil. Paraffinic oil can be refined to various levels including group I, group II and group III base oils.

Penetrant –

  • A thin type of oil used to penetrate into tight spaces and lubricate things such as bolt threads and cables.

Pitting –

  • A type of surface fatigue caused by a variety of surface interactions occurring on the surface of metal components. Pitting is sometimes divided into macropitting and micropitting. Micropitting appears are surface roughness on previously smooth surfaces. Macropitting is identifiable by visible “pits” eroded from metallic surfaces.

Polarity –

  • A property of certain base fluids and additives that contributes to multiple other properties. High levels of polarity can assist in solvency and additive compatibility. It can also result in molecules that are attracted to metal surfaces, forming stronger fluid films.

Pour Point –

  • The lowest temperature at which a material displays fluidity in less than 5 seconds when inverted at a 90 degree angle.

Precipitate –

  • When one material in a solution separates from another. When speaking about lubricants, this is usually in regard to an additive separating from the rest of the oil. Contamination and oil degradation are the typical causes of additive separation.

Reference Oil –

  • A fluid specified by certain standardized tests to give consistent results to said test. These are commonly used by the ASTM, SAE, JALOS and ACEA in their tests. The reference values obtained with these fluids are often used for calibration and reference points for test result interpretations.

Repeatability –

  • The tendency of a test to obtain similar results when performed by the same person, in the same laboratory.

Reproducibility –

  • The tendency of a test to obtain similar results when performed by different people, in different laboratories. The ability to reproduce or duplicate a test.

SAE #2 Clutch Test –

  • A bench test utilizing clutch plates and frictional materials to approximate the multi-plate wet clutches commonly used in motorcycles. This test uses friction measurements to classify oil’s friction modifying properties.

Safety Data Sheet (SDS) –

  • A document formally known as a Material Safety Data Sheet (MSDS) that conveys safety information about products. They include information about environmental, health, shipping and handling issues. Any hazardous components of a mixture must be disclosed on an SDS.

Shaft Drive –

  • A type of final drive component that uses a set of bevel gears and a drive shaft to rotate the rear wheel.

Shear Stability –

  • The affinity for an oil to maintain the size of its molecules and not have them sheared or cut. This action of shearing is very common in transmissions and consequently shear stability is especially important for motorcycle oils.

Shear Stability Index (SSI) –

  • A measurement of the shear stability which corresponds to the percentage of viscosity loss after shearing has occurred. Multiple tests can be used to determine the SSI of a polymer.

Sludge –

  • A byproduct of oil degradation. It is typically formed from the oxidation of base oil and additives. Sludge is a “heavy” portion of used oil and often settles to the bottom of an oil reservoir.

The Society of Automotive Engineers (SAE) –

  • A professional organization that regulates various viscosity grades of engine oils and gear/transmission oil weights.

Solid Lubricant –

  • A type of additive, usually in the form of a powder that provides a physical lubricating medium. These additives are usually used for extreme pressure protection and provide high resistance to wear and surface damage.

Solubility –

  • The ability of a fluid to dissolve or mix with other chemicals.

Stabilizing Additives –

  • Additives whose purpose is to inhibit permanent changes to lubricants. These include things like antioxidant, dispersant and acid neutralizing additives.

Static Friction Index (SFI) –

  • A test result that is part of the JASO 4-stroke motorcycle engine oil specification to classify an oil’s wet clutch frictional performance. The SFI is an indicator of how much force can be applied to an already engaged clutch before slippage occurs.

Static Friction (stiction) –

  • The friction that exists between two unmoving surfaces. This friction force must be overcome in order for those surfaces to slide over one another.

Stop Time Index (STI) –

  • A test result that is part of the JASO 4-stroke motorcycle engine oil specification to classify an oil’s wet clutch frictional performance. The STI measures how quickly a clutch engages from stand-still.

Sulfated Ash –

  • A test used to determine how much metallic ash remains after an oil is burned. This is one portion of evaluating an oil’s cleanliness and resistance to forming deposits.

Tackifier –

  • A category of additives that increase the surface tension of fluids to make them more sticky and adhesive.

Total Value –

  • The complete cost of using a product. This takes into account the up-front cost, the lifespan of the product and the level of its performance.

Tribofilm –

  • A chemical film formed by a lubricant on a surface that prevents direct contact between two surfaces.

Tribology –

  • The study and science of friction, lubrication and wear.

Under-lubrication

  • A situation where two contact points are not being properly lubricated. This can occur during lubricant starvation or there is a lack of lubricant or because of an inadequate or improper lubricant being used.

Used Oil Analysis or UOA –

  • An analytical review of conditions and properties of used oil for the purpose of identifying problems or condition monitoring of equipment.

Viscosity Index –

  • A number which is calculated using the kinematic viscosity of a fluid at varying temperatures. Simply put, it is a measure of how stable the viscosity is over a wide temperature range. The higher the viscosity index number is, the more stable a fluid is.

Viscosity Modifier –

  • Viscosity modifier (VM) or viscosity index improver (VI improver) is a type of polymer fluid used to, you guessed it, modify the viscosity of an oil somehow. Whether to give it higher viscosity at high temperatures or lower viscosity at low temperatures, they may be used for different purposes in different applications. VM or VI improvers are typically considered a type of base fluid.

Viscosity Stability –

  • A property of a fluid to retain its original viscosity throughout use. The resistance of a fluid to increase or decrease in viscosity due to usage.

Wet Clutch –

  • A clutch that is supplied with oil in order to lubricate and cool the clutch components.

Wrist Pin –

  • A stud located at the top of the connecting rod and acts as a bearing between the piston and the rod.

Zerk Fitting –

A fitting attached to a piece of machinery that acts as an adaptor port for grease guns. This fitting allows for grease to flow in only one direction.