Flash Point is referred to the minimum temperature of a petroleum product or other combustible fluid at which vapor is produced at a rate sufficient to yield a combustible mixture. Specifically, it is the lowest sample temperature at which the air-vapor mixture will “flash” in the presence of a small flame.

Flashpoint can indicate the possible presence of highly volatile and flammable materials in a relatively non-volatile or non-flammable material. For example, an abnormally low flash point on a test specimen of engine oil can indicate gasoline contamination The flash point can be used to determine the transportation and storage temperature requirements for Lubricants.

The shade and intensity showed when lubricating oil is viewed under specific conditions. The test is used for manufacturing control purpose and is important since the color is readily observed by the customer. The color of the lubricating oil is not always a reliable guide to product quality and should not be used indiscriminately by the customer in writing specifications for purchase. Where the color range of grade is known, a variation outside the established range indicates possible contamination with another product.

Sulfated ash is defined as the residue remaining after a sample has been carbonized (i.e. combusted), and the residue subsequently treated with sulphuric acid and heated to constant weight This test method covers the determination of the sulfated ash from unused lubricating oils containing additives and from additive concentrates used in compounding. These additives usually contain one or more of the following metals: barium, calcium, magnesium, zinc, potassium, sodium, and tin. The elements sulfur, phosphorus, and chlorine can also be present in the combined form.

For countries that possess cold weather climates, the performance of Lubricants in lower temperatures is of great importance. The pour point of a Lubricants is defined as the lowest temperature at which movement of the test specimen is observed under the prescribed conditions of the test. A reduction in the pour point can be achieved through the use of so-called pour point enhancers to “winterize” the fuel. The pour point of a Lubricants is the lowest temperature at which the Lubricants will pour or flow when it is chilled without disturbance under specified conditions.

Measurement of a fluid resistance to flow under gravity at a specific temperature (usually at 40° change into 40° C and 100° C).

A measure of a fluid’s change of viscosity with temperature is called Viscosity Index (VI). The higher the viscosity index the smaller the change in viscosity with temperature. Higher the viscosity index indicates the smaller change in viscosity with increasing temperature of the lubricating oil.

Specific gravity is the ratio of the weight of a given volume of a substance to the weight of an equal volume of water at stated temperature. Accurate determination of the density, relative density (specific gravity), or API gravity of petroleum and its products is necessary for the conversion of measured volumes to volumes or masses

It is used to measure the volume of fluid.

The amount of perchloric acid expressed in the term as the equivalent weight of milligram of KOH required to titrate the basic constituents present in 1 gram of sample is the Total Base Number. Total base number (TBN) is a measure of a reserve alkalinity of a Lubricants.

The test is relevant to internal combustion engines due to the acidic by-products of combustion generated when gasoline and diesel fuels are burnt. These by-products, including SOx, NOx, and others enter the crankcase via blow-by gases getting past the piston rings.

In addition to acids entering the engine crankcase from blow by, acids are normally generated in other areas of the engine due to heat, oxidation, and other chemical processes.

In an effort to counter the corrosive effect of acids on engine parts, constituents are added to the oil (oil additives) that have basic properties. As bases, they act to neutralize the acids in the engine. The additive commonly used is calcium sulfonate. Others, however, including magnesium sulfonate, phenates, and salicylates are also used. In addition to contributing to the TBN of a Lubricants, these additives are multifunctional in that they are also highly valued as dispersant additives.

In an effort to strike a balance, the total base number of new oil is typically in the range of 7 to 10 for gas engines and 10 to 14 for diesel engines. When the TBN in used oil drops below 3, it typically indicates the need for an oil change.