A short dictionary of basic terms

Base oil - the base of finished oil, one of its main components. It has the greatest influence on the properties of the final product. It is the base oil that determines "how much synthetic" the product will be. Base oils are divided into five groups: mineral, semi-synthetic, hydrocracking, PAO-synthetic and "non-petroleum" synthetic.

Direct injection – the electronic fuel system of a gasoline engine, structurally very similar to the Common Rail system in diesel engines. In direct injection systems, fuel, unlike a "classic injector", is not injected into the intake manifold, where it mixes with air and enters the combustion chamber through the intake valve, but directly into the engine cylinders under very high pressure. This allows for layered formation of the mixture already in the combustion chamber itself and layered and multi-stage combustion of the fuel-air mixture, which, with precise adjustment of the engine control system, ensures more complete combustion of fuel, reduction of emissions of harmful substances and improvement of engine fuel economy.

Evaporation – One of the characteristics of the oil that affects its consumption. Oil, like any liquid, evaporates over time. The rate of evaporation of automotive motor oils is 15%. At the same time, the evaporation rate of high-class motorcycle oils is regulated at the level of 6%.
Evaporation also indirectly indicates the quality of the base oil used.

Viscosity - one of the basic characteristics of oil properties, determines its fluidity. Oil viscosity is divided into kinematic and dynamic (HTHS).
Kinematic viscosity determines the fluidity of the oil itself, its density and, according to the SAE J300 specification, is divided into "cold" (winter) and "hot" (at a temperature of 100*C). Depending on the actual properties of the oil, it is assigned one of the viscosity classes. Each viscosity class corresponds to a certain range of actual oil viscosity values.

Dynamic viscosity (HTHS) determines the stability of the oil film and its density in a dynamic environment. The abbreviation HTHS fully describes the conditions under which the measurements are performed - this is high temperature at high shear speed (High Temperature High Shear). Physically, it is the product of kinematic viscosity and its density, measured in centipoise (cP).
According to the parameter of dynamic viscosity, it is generally accepted to divide oils into two classes: fully viscous with a value of HTHS >3.5 (the so-called standard viscosity of HTHS) and low viscosity with a value of HTHS < 3.5. it should be noted that the use of oils with low dynamic viscosity (reduced HTHS) in engines designed for such oils does not lead to additional wear. The use of full-viscosity oils in such engines, although it does not lead to additional wear, however, as a rule, leads to a decrease in engine power and economy, and also does not have a better effect on the operation of hydraulic tensioners, variable valve timing systems (VVT-I, VTC, CVVT).
In recent years, there has been a gradual transition of all car manufacturers to the use of low-viscosity oils in new engine models.

Ash content is sulfate - one of the parameters that characterizes the washing-dispersing properties of the oil, its ability to neutralize acids formed during fuel combustion, to keep insoluble combustion products in a suspended state, to prevent them from settling and settling on engine components in the form of high- and low-temperature deposits
When using fuel with a high sulfur content, the increased ash content and alkalinity of the oil prevent the formation of deposits. However, too high an oil ash content leads to increased wear of the engine due to the abrasive effect on the friction vapors, the formation of ash deposits in the combustion chamber, a decrease in the detonation resistance of the fuel, and the temporary failure of exhaust gas recirculation systems and particulate filters.
According to the content of sulfated ash, motor oils are divided into full-ash (with an ash content of 0.8-1.5%) and low-ash (ash content <0.8%). The unofficial class includes so-called medium-ash oils with a sulfate ash content of 1.0-1.2%.

Viscosity index (viscosity index) is a dimensionless value and reflects the stability of the temperature properties of the oil. The higher it is, the more stable are the viscosity characteristics of the oil when its temperature changes.

Viscosity class (viscosity grade) is a conventional designation of a complex of oil properties, the main of which is its kinematic viscosity. In accordance with the SAE J300 standard, motor oils are divided into 13 viscosity classes from 0W to 60, and transmission oils from 70w to 140. When indicating the kinematic viscosity, the "cold" viscosity is first indicated (SAE 0w, 5w, 10w , 75w, 80w, etc. where “w” means winter), then “hot” (SAE 20, 30, 40, 90, etc.). All-season oils are indicated by two indexes (5w30, 5w40, 10w40, etc.). The lower the viscosity class of the oil, the lower its corresponding viscosity. The main parameter in determining the cold viscosity of the oil is its pumpability and rotatability. The hot viscosity of the oil is determined at a temperature of 100*С.

Alkaline number (TBN) - one of the characteristics of the oil, which strongly indicates its cleaning properties. In the process of fuel combustion in the engine, acids are formed, which cause corrosive wear and carbon deposits. To neutralize them, alkali is used, the amount of which in the oil is determined by the alkaline number. The lower the quality of the fuel, the higher the alkaline number of the motor oil should be.
The alkaline number of cargo oils can reach 15 or more mgKOH/g, and for energy-saving light oils, the value is limited to 6 mgKOH/g.

Pump nozzle (Pumpe-Düse, PD) is an electronic diesel engine power system developed by the Volkswagen AG concern. It is a system in which a high-pressure fuel pump and a nozzle are structurally combined in one node. Thus, the fuel injector is simultaneously a fuel pump for itself. The system was used in the 2000s in cars of all brands of the concern, but due to lower reliability and high maintenance costs, it was later replaced by Common Rail.

Additives – additional additives to the base oil that improve, supplement its characteristics or give it additional properties. A balanced and verified complex of additives is part of any modern oil - motor, transmission, hydraulic, industrial.
The chemically and physically verified complex is a package of additives that gives the finished oil a set of certain properties.

Oil rotation (Low Temperature Cranking Viscocity) - an additional parameter that characterizes the low-temperature properties of the oil, determines the possibility of turning the crankshaft of the engine. The actual value is determined by the ASTM D5293 test standard. In connection with the non-linearity of the temperature properties of oils, pumpability is determined by the properties of oils, rotation is determined at different negative temperatures for different viscosity classes. The smaller this parameter is, the better the low-temperature properties of the oil.

Oil pumping capacity (Low Temperature Pumping Viscosity) is one of the key parameters of the low-temperature properties of the oil. The actual pumpability of the oil is determined by the ASTM D4684 test standard and indicates the minimum temperature at which the density of the oil is no more than 60,000 mPa.s. The pumpability of the oil is checked after exposure to a negative temperature corresponding to its viscosity class for 45 hours. The smaller this parameter is, the better the low-temperature properties of the oil.

Soot filter

Flash point (flashpoint) is a key parameter that characterizes the consumption of oil per burn. In the process of engine operation, oil vapors prone to ignition are formed when they come into contact with air. The higher the flash point of the oil, the higher its vapors are ignited at a higher temperature, and the lower the oil consumption per soot under standard engine operating modes. Less carbon black, in turn, reduces the amount of soot in the engine. Flash point also indirectly indicates the quality and grade of base oils and additive packages used.

Solidification temperature (pourpoint) is one of the main parameters that characterizes the low-temperature properties of the oil. Determines the temperature at which motor oil changes from a liquid state to a jelly-like state, begins to crystallize. The lower the purpoint, the lower the temperature it is possible to start the engine without its critical wear.

AdBlue – the working fluid of the SCR system of selective catalytic neutralization of exhaust gases. It is a 32% aqueous solution of urea. The liquid is very sensitive to the temperature regime of storage and operation and the quality of the water used to prepare the solution. The use of liquid that has been at temperatures exceeding the norms established for it can cause a decrease in the efficiency of the engine, an increase in fuel consumption, and mechanical malfunctions.

Common Rail – electronic diesel engine power system developed by Bosch. Structurally, it is very similar to the direct injection system in gasoline engines. In the Common Rail system, all fuel injectors are connected to one (or to two in some V-shaped engines) fuel rail, the pressure in which is maintained by the PNVT (high-pressure fuel pump). The injectors are controlled by the electronic engine control unit. It is the most common power supply system for diesel engines today.

DPF (diesel particulate filter) – a hard particle filter installed in the exhaust tract of modern diesel engines of cars and trucks. Reduces exhaust toxicity by capturing solid products of diesel fuel combustion, soot. Visually similar to the catalyst, but larger in size. On some cars, it is structurally made of one part with a catalyst. Is picky about the motor oil used - it must have a reduced ash content (ACEA C3, C4, ILSAC, etc.)

EGR (exhaust gas recirculation) – system of recirculation and afterburning of exhaust gases of gasoline and diesel engines. It is a valve that connects the exhaust tract with the post-throttle space of the intake tract. It is one of the most effective ways to reduce exhaust toxicity. The return of part of the exhaust gases to the intake manifold lowers the maximum combustion temperature of the fuel-air mixture and reduces the rate of formation of nitrogen oxides. The operation of the system does not significantly reduce the effective power of the engine. The system works in the modes of partial load on the engine and does not turn on at idle speed, on an unheated engine and when the throttle is wide open. EGR is not used on turbocharged gasoline engines.

HTHS - see Viscosity is dynamic

Pumpe-Düse - see Pump nozzle

TBN - see Alkaline number

SCR (selective catalytic reduction) – a system of selective catalytic neutralization of exhaust gases from diesel engines. The principle of SCR operation consists in the chemical transformation of exhaust gases into harmless substances - water and nitrogen. The system injects the active substance (catalyst) adBlue directly into the exhaust tract of the car, where a chemical reaction takes place. In addition, the use of the SCR system allows you to reduce fuel consumption on the 3-5%, which is especially noticeable on heavy trucks and highway tractors. The consumption of the active substance is 4-5% of the volume of spent fuel.

The chemical reaction in the SCR system proceeds in two main stages.
At the first stage, the AdBlue solution is injected into the hot exhaust gases, where the hydrolysis process occurs with the formation of ammonia: (NH2)2CO + H2O => 2 NH3 + CO2
During the second stage, decomposition into nitrogen and water occurs:
4NH3 + 4NO + O2 => 4N2 + 6H2O
8NH3 + 6NO2 => 7N2 + 12H2O

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