Glossary of Terms

A - B - C - D - E - F - G - H - I - L - M - N - O - P - R - S - V

A
ACID NUMBER
A number indicating the amount of free acid in a substance. Certain additives impart acidity in new oil. In service, used oils will show increasing acidity as the result of oxidation and, in some cases, additive deletion.
ADDITIVES
Chemicals which are added in small quantities to a lubricating oil or grease for the purpose of imparting new properties or enhancing those properties.
AGMA
American Gear Manufacturers Association. The association has published standards for gear lubricants, designating the lubricants by AGMA numbers.
ANILINE POINT
The temperature at which a true solution of equal parts of aniline and oil begin to separate into its two components liquids. Used in some specification to indicate the aromatic content of oils and the effect of swelling or shrinking oil seals. Aromatic and naphthenic containing oils have lower aniline points. Paraffinic oils have higher aniline points. API GRAVITY An arbitrarily chosen scale in which the specific gravity (density) of pure water is taken as 10; liquids lighter than water having values less than 10.
ASH
The ash or nonvolatile, incombustible content left after complete burning of lubricating oil. Generally expressed as weight percent
ASPHALT
Solid or semisolid petroleum products found naturally or obtained as a residue from the distillation of a naphthenic (asphaltic) base crude.
ASTM
American Society for Testing Materials. A group which establishes a standard methods of testing and interpreting tests relating to all types of materials. Committee D-2 establishes test methods relating to petroleum products.

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B
BASE STOCKS
Refined petroleum materials which are blended with other oils and additives to produce finished products.
BLACK OIL
Lubricant containing asphaltic materials, processing natural adhesiveness. Generally used on a once-through basis in noncritical applications.
BLEEDING
The tendency of a liquid component to separate from a liquid-solid or semisolid mixture, as oil from lubricating grease in storage or use.
BLEEDING
The process of mixing lubricant components for a purpose of obtaining desired physical (viscosity, VI, etc) and/or chemical properties (EP, oxidation resistance, etc.).
BRIGHT STOCKS
Heavy, fully refined residuals used as lube oil blending stocks. Has a "bright" bloom in reflected natural light.

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C
CALCIUM SOAP
A soap used as a grease thickener (see Grease). Characteristics of grease are relatively low melting point, high water resistance and smooth texture.
CARBON RESIDUE
The amount of carbonaceous materials left in all oil after destructive distillation (evaporation to coke) in absence of oxygen.
CETANE INDEX
An approximation of cetane number based on API gravity and mid-boiling point of fuel.
CETANE NUMBER
A measure of ignition quality of diesel fuel. The higher the cetane number the better and quicker the ignition, with less tendency to "knock". The higher the cetane of a fuel, the lower the octane number.
CLOUND TEST
The temperature at which paraffin wax or other solid substance begin to crystallize or separate from solution. Usually associated with diesel fuel and heating oil and their tendency to wax coat a filter at some temperature, thereby restricting fuel flow.
COLD TEST
The temperature at which oil becomes solid. Generally considered to be 5°F. Lower than the pour point. (See Pour Point).
COMPOUNDED OIL
Petroleum oil to which some animal or vegetable oil has been added.
CONSISTENCY
The degree of solidity or fluidity of a substance.
CRUDE OIL (PETROLEUM)
An earth-derived, naturally occurring mixture consisting predominantly of hydrocarbons (combinations of the elements of hydrogen and carbon). Components range from highly volatile to heavy viscous materials.

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D
DEMULSIBILITY
A measure of a lube oil's ability to separate from water. Expressed as test time required for a specific oil-water emulsion to break.
DETERGENT ADDITIVE
A substance incorporated in lubricating oil which has the property of keeping insoluble matter in suspension and preventing its deposition where it would be harmful.
DEWAXING
Removal wax from lube oil stock in the refinery.
DIESEL CETANE INDEX
An approximation of the cetane number of a fuel; the product of the API gravity and the aniline point (degree F. divided by 100). May give distored results with fuels of unusual chemical composition.
DISPERSANT
An oil additive that keeps insoluble foreign materials suspended throughout the oil. Generally used interchangeable with detergent.
DISTILLATE
Broadly, any distilled petroleum products as contrasted to a residual product.
DISTILLATION
Vaporization by heat, then condensation by cooling in separate chamber. The principal method by cooling in separating petroleum components of different boiling points.
DROPPING POINT
The temperature at which a drop of grease falls from the orifice of a test apparatus under a definite test procedure. This test has limited bearing upon service performance and should not be regarded as the melting point of the grease.

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E
EMULSION
An intimate mixture of oil and water through the use of emulsifier additive which resists separation by settling.
EP (EXTREME PRESSURE)
The quality of an oil or grease, imparted by additives, which enables it to withstand loads greater than it could if it did not contain the additives.

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F
FILLER
Any substances, such as talc, mica, moly or various powders which is added to a grease to satisfy some service application. Fillers increase the weight and consistency of grease.
FILM STRENGTH
The property of a lubricant which enables it to maintain an unbroken film between lubricated surfaces under operating conditions, thus avoiding scuffing or scoring of the surfaces, as in a bearing.
FIRE POINT
The minimum temperature at which vapor is produced at a sufficient rate to sustain combustion.
FLASH POINT
Minimum temperature of a petroleum product at which vapor is produced at a rate sufficient to yield a combustible mixture.
FLUSHING OIL
Oils used to remove oil, decomposition products and dirt from lubrication passages, reservoirs, etc.

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G
GREASE
A lubricant of semisolid to solid consistency made from a lubricating oil thickened with a metallic-organic soap such a sodium, calcium, aluminium, lithium, or combination thereof, or a non-soap material such as metallic sulfonates, treated bentonite clay, fumed silics or finely dispersed plastics.

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H
HEART CUT
In refining, a narrow boiling range fraction, usually picked near the middle portion of the stock being processed.
HEAVY DUTY OILS
Motor oils developed for use in certain types of high speed diesel engines and spark ignition engines subject to heavy loads and high operating temperatures. Engines service classification CC-CD-SD-SE identify these oils.
HYDRAULIC FLUID
Liquid of petroleum or non-petroleum origin used as a hydraulic medium.
HYDROCARBON
Compounds composed of only hydrogen and carbon atoms.

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I
INFRARED TEST
A laboratory test for identifying oil type, additive, contamination and oxidation products in new or used oils through the use of infrared light.
INORGANIC COMPOUND
Any compound containing no carbon. The exceptions are metallic carbonates which are considered an organic.

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L
LITHIUM SOAP
A soap used as a grease thickener (see Grease). Characteristics of lithium soap greases are high melting point, water resistance and smooth consistency.
LUBE OIL
Industry term for petroleum lubricating oils.
LUBRICATION OIL
Selected liquid fraction or blends of refined petroleum oils used to lessen friction between moving surfaces.

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M
MILLED GREASE
A grease which has undergone mechanical shearing of soap fibers to enhance oil absorption and retard oil bleeding.
MINERAL OIL
Any oil mineral origin, as petroleum.

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N
NAPHTHENIC BASE CRUDES
Crude oil containing a relatively large percentage of naphthenic type hydrocarbons, sometimes called asphalt base since relatively large quantities of asphalt can be derived from this type of crude. Oils derived from these crudes normally have a low viscosity index.
NEUTRAL OILS
Distillate lubricating oils with viscosity usually not above 200 SU AT 100°F and refined by distillation and filtration only.
NLGI NUMBER (NATIONAL LUBRICATING GREASE INSTITUTE)
A numerical scale for classifying the consistency range of lubricating grease and based on the ASTM penetration number. The higher the penetration number, the lower the NLGI number and the softer the grease.

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O
OCTANE NUMBER
A measure of anti-knock properties of gasoline.
ORGANIC COMPOUND
Compound of carbon, hence hydrocarbon.
OXIDATION
Chemical combination of any substance with oxygen.

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P
PALE OIL
A distillate oil, straw or pale yellow in color, either a finished oil or to be further refined.
PARAFFINIC CRUDE
Crude oil containing a high percentage of saturated aliphatic or paraffinic hydrocarbon molecules.
PENETRATION
An arbitrary measure of grease consistency based on ASTM test. All penetration measurements are in an inverse scale of consistency; that is, the softer the consistency, the higher the penetration number.
POUR POINT
The lowest temperature at which an oil will flow when it is chilled without disturbance under prescribed condition.
PPM
Part per million, usually by weight.
PRECIPITATE
A substance separating in solid form a liquid as the result of some physical or chemical change.

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R
RED OILS
Term used to describe an intermediate grade lubricating oil which is naturally red in color by transmitted light.
RESIDUAL STOCK
Heavy materials remaining in the bottom of the distillation tower after certain light products are distilled out.

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S
SAE NUMBER
Classification of motor, transmission and differential lubricants to indicate viscosity, standardized by the Society of Automotive Engineers.
SOAP
Any metallic salt of a fatty acid.
SODA SOAP
A sodium soap such as sodium stearate, used as a grease thickener (see Grease). Such grease have relatively high dropping points and should be used in dry application as sodium soap will absorb water.
SPECIFIC GRAVITY
The ration of the weight of any substance to the weight of an equal volume pf a substance taken as a standard. The standard is water for liquids or air for gases. SSU Saybolt Seconds Universal, sometimes expressed as SUS. A measure of viscosity at a given temperature.
STRAIGHT RUN
A product obtained by distillation with cracking or compounding with other products. Usually applied to gasoline and diesel fuel.
SULFONATES
A group of petroleum hydrocarbon derivatives resulting from treating oils with sulphuric acid or aynthesis. Used as synthetic detergent, emulsifying and wetting agents, chemical intermediates, grease thickeners and oil and grease additives.
SYNTHETIC LUBRICANT
A lubricant produced from man-made components rather than by extraction or refinement of naturally occurring petroleum fractions.

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V
VAPOR PRESSURE
A measure of the liquids' volatility. The higher this value, the more volatile the sample and the more readily it will evaporate. Reid vapor pressure plays a role in gasoline performance.
VISCOSITY
The measure of the internal friction or resistance of an oil to flow. In Petroleum usage, viscosity is often expressed as Saybolt Seconds Universal (SSU) or kinematic viscosity, expressed in centistokes (cSt) at a standard temperature. E.g., 100°F or 210°F. The higher the viscosity, the les fluid the liquid.
VISCOSITY INDEX (VI)
A scale showing the magnitude of viscosity change of a fluid with change in temperature. The higher the VI the less change in viscosity with temperature variations.

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