Synthetic Motor Oil
First to develope an API-rated 100 percent synthetic motor oil.

Glossary: AMSOIL Glossary

Abrasion

The wearing, grinding, or rubbing away by friction. Abrasion is usually due to the presence of foreign matter such as dirt, grit or metallic particles in the lubricant

Absolute Viscosity

The product of Kinematic Viscosity and Density. Absolute Viscosity (n) = Kinematic Viscosity (y) x Density (p).

ACEA

Association of European Automotive Manufacturers

Acid

Corrosive solution formed by the combination of hydrogen and oxygen atoms with metal or metallic radicals. Acidic solutions may be neutralized with a base or alkaline solution.

Acid Number

A measure of the amount of KOH needed to neutralize all or part of the acidity of a lubricant

Additive

Material added to a base stock to change its properties, characteristics or performance.

Adhesion

The property of a lubricant that causes it to cling or adhere to a solid surface. Wear occurring when surfaces contact, weld together and shear off.

AGMA

American Gear Manufacturers' Association

Air Entrainment

Ambient Temperature

Temperature of the air surrounding the point of application.

Anhydrous

Free of water.

Antifoam

Additive used to suppress the foaming tendency of lubricants in service. Improper amounts of antifoam will lead to air entrainment, which also leads to lubrication problems.

Antifreeze

Solution in an engine cooling system that lowers the coolant's freezing point and raises its boiling point.

Antioxidant (oxidation inhibitor)

An additive that retards oxidation of lubricants.

Antiwear

Additives that form thin tenacious films on loaded parts to prevent metal-to-metal contact.

API

American Petroleum Institute

Apparent Viscosity

A measure of the viscosity of a non-Newtonian fluid under specified temperature & shear. Viscosity is expressed in units of centipoise (cP).

Ash

Metallic deposits formed in the combustion chamber and other engine parts during high temperature operation.

Ash (Sulfated)

The ash content of an oil, determined by charring the oil, treating the residue with sulfuric acid, and evaporating to dryness. Expressed as % per mass.

ASLE

American Society of Lubrication Engineers

ASME

American Society of Mechanical Engineers

ASTM

American Society for Testing and Materials

Ball Bearing

A class of bearing in which the moving surface is separated from the stationary surface by elements in the form of balls.

Base Number

The amount of acid needed to neutralize all or part of a lubricant's basicity.

Bases

Compounds that react with acids to form salts plus water. Alkalis are water-soluble bases used in petroleum refining to remove acidic impurities. Oil soluble bases are included in lubricating oil additives to neutralize acids formed during the combustion of fuel or oxidation of the lubricant.

Bearing

An object that supports weight and reduces friction by allowing a surface to rotate or slide when under load.

Biodegradable

Ability of a material can be broken down, within given parameters of time and environment, by naturally occurring bacteria into simple substances, which do not harm the environment.

Bleeding

Separation of liquid lubricant from a grease.

Blow-by

Passage of unburned fuel and combustion gases past the piston rings of internal combustion engines, resulting in fuel dilution and contamination of the crankcase oil.

Boundary Lubrication

Lubrication between two rubbing surfaces without the development of a full fluid lubricating film. It occurs under high loads and requires the use of antiwear or extreme-pressure additives to prevent metal-to metal contact.

BPT

Borderline Pumping Temperature

Brinelling

Denting caused by impact of one bearing component against another while stationary.

BTU

British Thermal Unit

By-Pass Filtration

A system of filtration in which only a portion of the total flow of a circulating fluid system passes through a filter at any instant or in which a filter having its own circulating pump operates in parallel to the main flow.

CARB

California Air Resources Board

Carbon Residue

Coked material remaining after an oil has been subjected to high temperatures.

Cavitation

The formation and collapse of vapor bubbles within a liquid.

CCS

Cold Crank Simulator

CEC

Conseil Européen de Coordination pour les

Centipoise (cP)

Unit of measure for apparent viscosity.

Centistoke (cSt)

Unit of measure for Kinematic Viscosity.

Cetane Index

A value calculated from the physical properties of a diesel fuel to predict its Cetane Number.

Cetane Index

A value calculated from the physical properties of a diesel fuel to predict its Cetane Number.

Cetane Number

Measure of ignition quality of a diesel fuel. The higher the Cetane Number, the easier a high-speed, direct injection engine will start, and the less "white smoking" and "diesel knock" after start up.

Cetane Number Improver

An additive that boosts the Cetane Number of a fuel while improving combustion efficiency and increasing power in a diesel engine.

Channel Point

See pour point. As you reduce the temperature of an oil toward the pour point, you reach a point where you can run your finger through an oil and it will not fill in the trench you leave behind. Example: the gearing in the rear end of a car. Although the gears might move, the gear oil will not flow back into the gear to lubricate it readily.

Chemical Stability

The tendency of a substance or mixture to resist chemical change.

Cleveland Open Cup (C.O.C.)

An apparatus used to determine the flash and fire points of petroleum products other than fuel oils and those having an open cup flash below 79ºC/175ºF.

Cloud Point

The temperature at which a cloud of wax crystals appears when a lubricant or distillate fuel is cooled under standard conditions. Indicates the tendency of the material to plug filters or small orifices under cold weather conditions.

CMA

Chemical Manufacturers Association

COC

Cleveland Open Cup

Coefficient of Friction

Number obtained by dividing the frictional force resisting motion between two bodies (F) by the normal force pressing the bodies together (L). m = F ¸ L

Cohesion

That property of a substance that causes it to resist being pulled apart by mechanical means.

Cold Cranking Simulator (C.C.S.)

An intermediate shear rate viscometer that predicts the ability of an oil to permit a satisfactory cranking speed to be developed in a cold engine.

Combustion Chamber

The space between the piston and cylinder head in an internal combustion engine where the charge of fuel plus air is burned to produce power.

Compatibility

A lubricant's ability to be mixed with another lubricant without detriment to either lubricant. Also, the ability to come into contact with other components or materials without detrimental effects.

Compound

Substance formed by the combination of two or more elements with differing physical and chemical properties than the combining elements.

Compression Ignition

Ignition of fuel by the heat generated in compressing the air charge, as in the diesel engine.

Compression Ratio

The ratio of the volume of combustion space at the bottom dead center to that at top dead center, in an internal combustion engine.

Consistency

The degree to which a semi-solid material such as grease resists deformation.

Contaminant

Any material that is unwanted or adversely affects the fluid power system and/or its components.

Coolant

Fluid used to remove heat. Commonly found in an engine's cooling system.

Copper Strip Corrosion

Qualitative measure of the tendency of a liquid to corrode pure copper.

Corrosion

Destruction of a metal by chemical or electo-chemical reaction with its environment.

Corrosion Inhibitor

Additive that protects lubricated metal surfaces from chemical attack by water or other contaminates.

cP

CentiPoise

Cracking

Refining process in which large molecules are broken down into smaller molecules. Cracking takes place to some extent whenever high molecular material is heated strongly, but can be increased by catalysts.

Crankcase

The housing in which the crankshaft and many other parts of the engine operate. On a two-cycle engine, the area in which the fuel/oil mixture is drawn before being transferred to the cylinder.

Crankcase Dilution

When unburned fuel finds its way past the piston rings into the crankcase oil, where it dilutes or thins out the engine lubricating oil.

Crude Oil

Naturally occurring petroleum, before any refining or treatment.

cSt

CentiStoke

Density

Mass per unit of volume.

Detergent

Additive to keep engine parts clean. In motor oil formulations, the most commonly used detergents are metallic soaps with a reserve of basicity to neutralize acids formed during combustion.

Detonation

Uncontrolled burning of the last portion (end gas) of the air/fuel mixture in the cylinder of a spark-ignition engine. Also known as "knock" or "ping".

Differential

Set of gears that transfers the power from the drive shaft to the drive wheels and allows those wheels to turn at different speeds. 

DIN

Deutsche Industrie Norm

Dispersant

Additive that helps keep solid contaminants in crankcase oil in colloidal suspension, preventing sludge and varnish deposits on engine parts. Usually nonmetallic ("ashless"), and used in conjunction with detergents.

Distillation

Separation of a mixture of liquids with different boiling points by progressively raising the temperature. In a refinery distillation unit the temperature rises continuously from the top to the bottom of the column and different fractions or cuts are drawn off at different heights.

Distillation Test

The basic test used to characterize the volatility of a gasoline or distillate fuel.

Drag

Resistance to movement caused by oil viscosity.

Dropping Point

Temperature at which a grease passes from a semi-solid to a liquid state under specified test conditions.

Drum

A cylindrical container that holds 55 gallons of oil or approximately 400 pounds of grease type products. There are also half-size drums that hold approximately 30 gallons of oil.

Dynamic Viscosity

Viscosity of a liquid as measured in a rotational instrument, as distinct from the kinematic viscosity where the liquid falls through a capillary tube under its own weight.

E.G.R. (Exhaust Gas Recirculation) Valve

System to reduce automotive emission of nitrogen oxides (Nox). It routes exhaust gases into the intake manifold where they dilute the air/fuel mixture and reduce peak combustion temperatures, thereby reducing the tendency for Nox to form.

EGR

Exhaust Gas Recirculation

EHD

Elastohydrodynamic Lubrication

EHL

Elastohydrodynamic Lubrication

Elastohydrodynamic Lubrication (EHD or EHL)

Lubrication characterized by high unit loads and high speeds in rolling elements where the mating parts deform elastically due to the incompressibility of the lubricant film under very high pressure.

Elastomer

A rubbery type of material. 

EMA

Engine Manufacturers Association

Emulsifier

Substance used to promote or aid the formation of a stable mixture, or emulsion of oil & water.

Emulsion

Mixture of two liquids, which are not soluble with each other, such as oil and water. 

Engine Deposits

Hard or persistent accumulation of sludge, varnish and carbonaceous residues due to blow-by of unburned and partially burned fuel, or the partial breakdown of the crankcase lubricant. Water from the condensation of combustion products, glycol, carbon, residues from fuel or lubricating oil additives, dust and metal particles also contribute.

EP

Extreme Pressure

EP (Extreme Pressure)

Lubrication regime where surfaces are sliding against each other under heavy load. The expression was coined for the condition present in hypoid gears in automotive rear axles.

EP (Extreme Pressure) Lubricants

Lubricants that impart to rubbing surfaces the ability of carrying greater loads than would be possible with ordinary lubricants without excessive wear or damage.

Erosion

The wearing away of a surface by an impinging fluid or solid

Ester

An organic compound formed by the reaction of an acid (organic or inorganic) with an alcohol. 

Ethanol

Ethyl alcohol mainly formed through fermentation. (alcoholic drinks, component in "gasohol")

Ethylene Glycol

A colorless, syrupy liquid, used as an antifreeze in cooling and heating systems.

Evaporation Loss

The loss of a portion of a lubricant due to volatization.

Fillers

A term normally used to denote something non-chemical added to an oil or grease, i.e., moly, graphite, zinc oxide.

Film Strength

The ability of a lubricant film to withstand the effects of speed, temperature and load without breaking down.

Filter

Any device or porous substance used for cleaning and removing suspended matter from a gas or fluid.

Fire Point

The temperature where a lubricant, when subjected to a source of ignition or flame, ignites & continues to burn.

Fire Resistant Fluid

A fluid, difficult to ignite, that shows little tendency to propagate flame.

Flash Point (C.O.C.)

The temperature to which a combustible liquid must be heated to give off substantial vapor to form a momentarily flammable mixture with air when a small flame is applied under specific conditions.

Fluid

Liquid, gas or combination thereof.

Fluid Friction

Occurs between the molecules of a gas or liquid in motion, and is expressed as shear stress. Unlike solid friction, fluid friction varies with speed and area.

Fluid Power

Energy transmitted and controlled through use of a pressurized fluid within an enclosed circuit.

Foam

An agglomeration of gas bubbles separated from each other by a thin liquid film. If an oil is said to not foam, the small air bubbles will quickly combine, become larger bubbles, and then break to vent to the atmosphere. If this action occurs slowly, the oil is said to foam.

Four Stroke Engine

An internal combustion engine that requires two revolutions of the crankshaft to complete all four cycles.

Fretting

Wear resulting from small amplitude motion between two surfaces; may produce red or black oxide.

Friction

Resistance to motion of one object over another. Friction depends on the smoothness of the contacting surfaces, as well as the force with which they are pressed together.

Fuel Dilution

The amount of unburned fuel present in the lubricant. This test will indicate problems such as fuel line, injector, carburetor and pump leaks. Fuel dilution is accurate down to less than 0.5%.

Full Film Lubrication

Complete separation of mated surfaces. No metal-to-metal contact.

Full-Flow Filtration

A system of filtration in which the total flow of a circulating fluid system passes through a filter prior to component delivery.

Gears

Toothed machine parts for transmitting power from one shaft to another.

Gravity

The mass/volume relationship of lubricants used in determining volume requirements for specific mass of products (packaging).

Grease

Lubricant composed of an oil or oils thickened with a soap, soaps or other thickener to a semi-solid consistency.

Gum

A rubber like, sticky deposit black or dark brown in color resulting from the oxidation of lubricating oils from unstable constituents in gasoline, which deposit during storage or use.

High Temperature High Shear Rate Viscosity (HTHS)

A measure of a fluids resistance to flow under conditions resembling highly-loaded journal bearings in fired internal combustion engines, typically 1 million s-1 at 150oC.

Hydro finishing

A process for treating raw extracted base stocks with hydrogen to saturate them for improved stability.

Hydrocarbons

Compounds of hydrogen & carbon of which petroleum products are typical examples. Also known as organic compounds.

Hydrodynamic Lubrication

The formation of a continuous lubricating fluid film between mating surfaces of sufficient pressure to prevent contact

Hydrolytic Stability

Ability of additives and certain synthetic lubricants to resist chemical decomposition (hydrolysis) in the presence of water.

Hypoid Gear Lubricant

A gear lubricant having extreme pressure characteristics for use in hypoid type gears (as in the differential of an automobile).

ILSAC

International Lubricant Standardization and Approval Committee

Incompatibility

When a mixture of two or more substances shows physical properties or service performance characteristics, which are inherently inferior to those of either of the individual products before mixing.

Inhibitor

Additive that improves the performance of a petroleum product by controlling undesirable chemical reactions, i.e., oxidation inhibitor, rust inhibitor, etc.

Insolubles

Contaminates found in used oils due to dust, dirt, wear particles or oxidation products. 

ISO

International Organization for Standardization

JAMA

Japanese Automobile Manufacturers Association Inc.

JASO

Japan Automobile Standards Organization

Journal

Part of shaft or axle that rotates or angularly oscillates in or against a bearing or about which a bearing rotates or angularly oscillates.

Keg

Container which would typically hold 16 gallons of oil or approximately 120 pounds of a grease-type product. Also called a "quarter drum".

Lubrication

Control of friction and wear by the introduction of a friction reducing film between moving surfaces in contact. May be a fluid, solid or plastic substance. 

Material Safety Data Sheet (MSDS)

Vital information regarding the safe handling and storage of a product.

Micron

A millionth of a meter, or 0.0000394 inch.

Mineral Oil

Term applied to a wide range of products that is typically used when referring to petroleum-based lubricants.

Mini Rotary Viscometer

An instrument used to measure the borderline pumping temperature (BPT) of engine oils from 0ºC to -40ºC. BPT is the lowest temperature at which engine oil can be supplied in adequate amounts to the oil pump inlet.

MSDS

Material Safety Data Sheet

Multi-viscosity/Multi Grade Oil

Engine or gear oil that meets the requirements of more than one SAE viscosity grade classification, and that can be used over a wider temperature range than a single grade oil.

Naphthenic

A type of petroleum fluid derived from naphthenic crude oil, containing a high proportion of closed-ring methylene groups.

Neutralization Number

A measure of the acidity or alkalinity of an oil.

Newtonian Flow

Occurs in a liquid system where the rate of shear is directly proportional to the shearing force, as with straight grade oils which do not contain polymeric viscosity modifier. When rate of shear is not directly proportional to the shearing force, flow is non-Newtonian, as it is with oils containing viscosity modifiers.

Nitration

Process where nitrogen oxides attack petroleum fluids at high temperatures, often resulting in viscosity increase and deposit formation. Nitration only occurs in applications where fuel is used.

NLGI

National Lubricating Grease Institute

NLGI

National Lubricating Grease Institute, an industry group that monitors grease and sets penetration standards for grading greases.

NLGI Number

A scale for comparing the consistency (hardness) range of greases.

NMMA

National Marine Manufacturers Association

Organic Acid

An organic compound, with acid properties, obtained from organic substances such as animal, vegetable and mineral oils, i.e., a fatty acid.

Oxidation

Occurs when oxygen attacks fluids. The process is accelerated by heat, light, metal catalysts and the presence of water, acids, or solid contaminants. It leads to increased viscosity and deposit formation.

Oxidation Inhibitor

Substance added in small quantities to an oil product to increase its oxidation resistance, thereby lengthening its service or storage life. Also called an antioxidant.

Oxidation Stability

Resistance of an oil product to oxidation and, therefore, a measure of its potential service or storage life.

Oxygenated Fuels

Fuels for internal combustion engines that contain oxygen combined in the molecule, e.g., alcohols, ethers and esters. Term also applies to blends of gasoline with oxygenates, e.g., Gasohol, which contains 10% by volume of anhydrous ethanol in unleaded gasoline.

PAO

Polyalphaolefin

Paraffin

Hydrocarbons belonging to the series starting with methane (CH4). Paraffins are saturated with respect to hydrogen. High molecular weight paraffins are solid such as paraffin wax.

Particle

A minute piece of matter with observable length, width and thickness, usually measured in micrometers.

PCV (Positive Crankcase Ventilation) Valve

An emissions control device that allows gases from the crankcase to be reintroduced into the intake.

Penetration

A test in which a cone is dropped into a grease sample to measure the penetration or how hard or soft the grease is at room temperatures. The cone penetrates farther in a soft grease and therefore has a higher penetration number. This penetration relates to an NLGI number. A number 0 grease is called an NLGI 0 grade and will be "softer" than an NLGI 1 or 2 grade.

pH

A measure of acidity or alkalinity. Values of pH run from 0-14; 7 indicating neutrality, numbers less than 7 indicate increasing acidity, and numbers greater than 7 indicate increasing alkalinity.

Pitting

Surface cavities, may be related to fatigue, overload or corrosion.

Pneumatics

Engineering science pertaining to gaseous pressure and flow.

Poise

Unit of viscosity, defined by the shear stress required to move one layer of fluid along another over a total thickness of one centimeter at a velocity of one centimeter per second. This viscosity is independent of fluid density, and directly related to flow resistance.

Polishing (bore)

Excessive smoothing of the surface finish of the cylinder bore or cylinder liner in an engine to a mirror-like appearance, resulting in depreciation of ring sealing and oil consumption performance.

Polymerization

Chemical combination of similar type molecules to form larger molecules.

Pour Point

An indicator of the ability of an oil or distillate fuel to flow at cool operating temperatures. It is the lowest temperature at which the fluid will flow when cooled under prescribed conditions.

Pour Point Depressant

Additive used to lower the pour point or lower the temperature fluidity of a petroleum product.

Preignition

Ignition of the fuel/air mixture in a gasoline engine before the spark plug fires. Often caused by incandescent fuel or lubricant deposits in the combustion chamber, it wastes power and may damage the engine.

Propylene Glycol

A non-toxic liquid used as a coolant/antifreeze in cooling and heating systems.

Pumpability

The low temperature, low shear stress-shear rate viscosity characteristics of an oil that permit satisfactory flow to and from the engine oil pump and subsequent lubrication of moving components.

Re-refining

A process of reclaiming used lubricant oils and restoring them to a condition similar to that of virgin stocks by filtration, clay adsorption or more elaborate methods.

Refining

Series of processes to convert crude oil and its fractions into finished petroleum products, which may include thermal cracking, catalytic cracking, polymerization, alkylation, reforming, hydrocracking, hydrofoaming, hydrogenation, hydrogen treating, Hydrofining, solvent extraction, dewaxing, de-oiling, acid treating, clay filtration, deasphalting, etc.

Ring Sticking

Freezing of a piston ring in its groove in a piston engine or reciprocating compressor due to heavy deposits in the piston ring zone.

Rust

Slow oxidation of iron.

Rust Preventative

Compound for coating iron surfaces with a film that protects against rust. Commonly used to preserve equipment in storage.

SAE

Society of Automotive Engineers

SAE Grade

Numbers applied to automotive lubricants to indicate their viscosity range.

Saybolt, Saybolt Universal Seconds, SUS, or SSU

The most common viscosity measurement prior to the international acceptance of centistokes, SUS measurements are now obsolete. To convert measurements from SUS at 100°F to an approximate value in cSt at 40°C (ISO viscosity grade), divide the SUS value by 5.

Scoring

Scratches on mechanical parts in the direction of motion caused by abrasive contaminants.

Scuffing

Abnormal engine wear due to localized welding and fracture. It can be prevented through the use of antiwear, extreme-pressure and friction modifier additives. See adhesion.

Semi Fluid

Any substance having attributes of both a liquid and a solid. Similar to semi solid but being more closely related to a liquid than a solid.

Shear Stability

Ability of a lubricant to withstand shearing forces without being degraded to lower viscosity or consistency.

Shearing

Relative slipping or sliding between one part of a substance and an adjacent part.

Sludge

A thick, dark residue, normally of mayonnaise consistency, that accumulates on nonmoving engine interior surfaces. Generally removable by wiping unless baked into a carbonaceous consistency, its formation is associated with insolubles overloading the lubricant.

Solid

Any substance having definite shape that it does not readily relinquish. More generally, any substance in which the force required to produce a deformation depends upon the magnitude of the deformation rather than the rate of deformation.

SSU

Saybolt Universal Seconds

STLE

Society of Tribologists and Lubrication Engineers

Stoichiometric

Ratio of fuel to air where the exact proportions for complete reaction of both, with none left over, are present. 

Surface Tension

The contractile surface force of a liquid by which it tends to assume a spherical form and to present the least possible surface. It is expressed in dyne/cm or ergs/cm.

SUS

Saybolt Universal Seconds

Synthetic Lubricant

Fluid made by chemically reacting materials to produce a lube with a specific chemical composition, which has planned, and predictable properties.

TAN

Total Acid Number

TBN

Total Base Number

Thermally Stable

Ability to withstand temperatures without decomposing. Not to be confused with oxidation stability where oxygen must be present and oxidation rather than decomposition. 

Thickener

The metallic soap or other material used to combine with oil or other lubricating fluid to make a grease.

Total Acid Number (TAN)

The quantity of base, expressed in milligrams, that is required to neutralize all acidic constituents present in one gram of sample.

Total Base Number (TBN)

The quantity of acid, expressed in terms of the number of milligrams that is required to neutralize all basic constituents present in one-gram sample.

Total Solids

The total amount of solids contamination, both suspended and non-suspended present in the lubricant. This test is indicative of carburetion problems (too rich or too lean), if the oil filter has reached the saturation point and is no longer able to remove contamination from the system, and if the air intake system is functioning properly and allowing enough air into the unit for complete burn to take place.

Tribology

Science of the interactions between surfaces moving relative to each other, including the study of lubrication, friction and wear.

Turbine

A device consisting of blades attached to a disc or rotor, which converts flow into rotary action.

Turbocharger

A device for increasing the pressure and hence the mass of air and fuel burned on each firing stroke. A turbine of exhaust gases drives a compressor; therefore, efficiency is variable and related to exhaust pressure.

Vapor Lock

Condition wherein the fuel boils in the fuel system forming bubbles that retard or stop the flow of fuel to the engine.

Varnish

A thin, insoluble, non-wipeable film occurring on interior engine parts.

VI

Viscosity Index

VII

Viscosity Index Improve

Viscosity Index (V.I.)

Relationship of viscosity to temperature of a fluid. High viscosity index fluids tend to display less change in viscosity with temperature than low viscosity index fluids.

Wear

Damage resulting from the removal of materials from surfaces in relative motion.

ZDP

Zinc Dithiophosphate