Industry Terminology

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The below are some of the widely used terms within the Lubricants Industry along with what we hope are some easy to understand explanations where ever possible.

Low SAPS ... meaning low Sulphated Ash, low Phosphorous and low Sulphur content in an engine oil.    The low SAPS formulations are a requirement to meet Euro 4 and Euro 5 Exhaust emmission controls

Monograde Oil ... this is an oil which does not contain any Viscosity Index Improvers (VII) or Viscositiy Modifiers (VM)

Multigrade Oils ... contain VII or VM to resist the thinning effect on the oils viscosity due to temperature.   Multigrade oils are widely used in modern engines and equipment.

SAE ... Society of Automotive Engineers, this is an Industry body for rating an oils viscosity primarily in automotive engine and gear oils, it is used to rate both Monograde and Multigrade oils.For example a SAE 30 is Mongrade and a SAE 20w/50 is a Multigrade.    The viscosity of a Monograde is given at 40 degree's Celsius only whilst the viscosiy of a Multigrade is given at 40 degree's Celsius (the lower figure) and at 100 degree's Celsius (the higher figure)

ISO ... International Standards Organisation, this is an Industry body for rating an oils viscosity primarily when it comes to Hydraulic and Industrial Gear oils.    The ISO viscosity rating is usually given at 40 degree's Celsius, for example the viscosity of an ISO 220 gear oil is 220 centistokes (cSt) @ 40 degree's Celsius or a Hydraulic 68 is 68 cSt @ 40 degree's Celsius

OEM ... Original Equipment Manufacturer means the actual manufacturer of your vehicle etc, the OEM's usually indicate or reccomend the type and specification of which oil you should use in your Equipment/Vehicle etc

Density or Specific Gravity (SG) ... Density means the volume weight of a substance. In oils, it is usually indicated in the temperature of +15C or +20C, in units kg/m3. Lubricant densities range between about 700 and 950 kg/m3, depending on the quality, viscosity and additive content of the lubricant.

Viscosity ... The thicker a fluid is, the greater its viscosity. Nowadays, lubricant viscosity is usually expressed with the units centistoke (mm2/s) and centipoise (mPas).

Centistoke (cSt) ... Centistoke is a unit of kinematic viscosity, based on the amount of force required to beat the internal friction of fluid.

 Centipoise (cP) ... Centipoise is a unit of dynamic viscosity, often used for expressing the internal friction of oil in low temperatures. The connection of cSt and cP is cP = cSt x fluid density. The temperature must always be given when expressing viscosity with any unit. All oils become much thinner as the temperature rises. A typical viscosity of motor oil SAE 10W at a temperature of -20C may be 2,000 cP, but if it heats up to a temperature of +100C the viscosity is only 5.2 cSt. Kinematic viscosity is measured by the pictured Ubbelohde viscometer. It measures the time the oil requires to flow from point m1 to point m2.

Viscosity index (VI) ... Viscosity index (V.I.) describes the fluid’s tendency to thin as the temperature rises. The stronger the fluid thinning the smaller the viscosity index. The V.I. of single-grade motor oils is about 95-110, and that of multi-grade motor oils even higher than 200.

Flash point ... The flash point expresses the flammability of a fluid. Flash point is the temperature at which, measured from the fluid with a certain method, flammable gases are vaporized so much that they flame up when ignited with a naked flame, but the fluid does not carry on burning.

Pour point ... Oil thickens as the temperature falls. At a certain temperature it no longer flows by its own weight. This temperature is called the pour point. The pour point depends on, e.g., the viscosity and chemical structure of the oil. In paraffinic oils, stiffening is caused by the wax in the oil, which is distinguishable as crystals. The more the oil cools down the bigger the crystals grow, eventually forming a flow-preventing network within the oil.

The pour point can be improved by using an additive that prevents the growth and interconnection of wax crystals. With the pour point, it is possible to describe approximately the cold start properties of oil, but in many cases it is not enough; it is more important to know the true oil viscosity at the starting temperature.