Operating conditions of engine oil
When operating a vehicle, engine oil operates under constantly changing conditions. Therefore, it is extremely difficult to accurately determine the influence of individual factors on the efficiency of an oil. In engines running for a long time at high speeds or at full load, the oil heats up to a high temperature. Under the influence of high temperatures and exposure to atmospheric oxygen, the oil begins to oxidize. Oxidation products lead to an increase in the density of the oil and can be deposited as a deposit on the upper surface of the cylinders, in the grooves of the sealing rings and on the valve stems. This can lead to the formation of soot on the valve plates.
If a rich mixture is supplied to the cylinders, and the engine rarely runs (or not working at all) at full load or does not reach normal operating temperature (e.g. when driving in the city), the result is incomplete combustion of the combustible mixture. Soot, oil deposits, unburned fuel and condensed moisture form deposits, acids and gums. Unburned fuel condenses on the cold walls of the cylinders and flows into the oil sump, washing away the thin oil film from the surface of the cylinders and pistons. As a result, the lubrication of the working surfaces of the pistons deteriorates and the oil liquefies, which impairs its lubricity.
If the oil is too thin, it may be necessary to change it ahead of time. Because when driving fast (with a hot engine) gasoline evaporates from the oil, then in winter it is recommended to check the oil level in the engine more often (more cold starts - more gasoline in oil).
Oil viscosity
Viscosity characterizes the fluidity of an oil. It changes depending on the ambient temperature. When heated, the oil becomes more fluid. This impairs its adhesiveness and oil film stability as pressure increases. When cooled, the oil thickens, i.e. its fluidity decreases and internal friction increases. Because of this property, it is necessary to use an engine oil with a viscosity that changes as little as possible with temperature changes.
When starting a cold engine, the oil must be thin enough so that it does not overload the engine unnecessarily and so that after starting it penetrates all lubricated places more quickly.
The viscosity of an oil is equivalent to its internal friction and is indicated by SAE units (Society of Automotive Engineers - Association of Automotive Engineers), for example, SAE 30, SAE 10, etc. A high SAE indicates that the oil is thick, while a low SAE indicates a thinner oil. However, viscosity alone does not provide information about the lubricating properties of an oil.
All-weather oil
It is recommended to use all-weather oils in all Opel Vectra/Calibra engines. The advantage of all-season oils is that they do not need to be replaced due to the changing seasons (summer Winter). These oils are produced on the basis of liquid seasonal oil (e.g. 15W). When heated, the oil is stabilized by so-called thickeners, which gives the appropriate lubricating properties at all ambient temperatures. If a multigrade oil is used, then modern oils with a wide viscosity range should be selected (e.g. 15W40, 15W50).
Oils with improved lubricity
Enhanced lubricity oils are multigrade oils that contain, among other additives, substances that reduce the coefficient of friction, resulting in reduced fuel consumption. Their production requires special raw materials (synthetic oils).
Applications for oils of various viscosities
A - seasonal oils;
B - all-weather oils;
С - all-weather oils with improved lubricating properties
Since the boundaries of the use of oils of neighboring SAE classes overlap with each other, short-term temperature fluctuations can be ignored when selecting an oil. If oil needs to be topped up and the oil in the engine no longer matches the outside temperature, oils of different viscosity grades can be mixed together.
Attention! Additional additives of any kind must not be added to oils or fuels!
Characteristics of engine oil
In modern engines, only HD quality oils are allowed. These are refined oils, the lubricating properties of which are significantly improved by adding various chemically active additives. These additives provide anti-corrosion protection of lubricated parts, increase the oil's resistance to oxidation, reduce the formation of deposits inside the engine, have a more stable viscosity, and also have detergent and solvent properties. Detergents and solvent additives not only reduce the formation of deposits in the engine (deposits), but at the same time they have the ability to dissolve them and disperse them together with other contaminants, which makes it possible to remove these contaminants when changing the oil.
The quality of engine oil is indicated in accordance with the API system (American Petroleum Institute - American Petroleum Institute). The designation consists of two letters. The first letter indicates the scope (S (Service) - for petrol engines. WITH (Commercial) — for diesel). The second letter characterizes the quality of the oil (In alphabet order). According to the API system, the highest quality oil is SH for gasoline engines and CF for diesel engines.
Attention! Engine oils of CF quality, which are intended for diesel engines, are not suitable for gasoline engines.
There are oils that can be used in both types of engines. In this case, two designations are indicated on the oil containers (e.g. SG/CD).
API SG or SH oils must be used for Opel Vectra/Calibra gasoline vehicles and CD oils for diesel engines.
European oil manufacturers use the CCMS designation system. It is used by European engine manufacturers and is becoming increasingly popular. Oils for gasoline engines, depending on the quality, are designated from G1 to G5, and for diesel engines - PD1 and PD2.
For its gasoline engines, Opel recommends the use of multigrade oils with a quality of at least G4. Class G5 consists of multigrade oils with improved lubricity and low viscosity. Both classes approximate the API SF class, meeting additional European requirements. The CCMC PD2 oil recommended by Opel for diesel engines is slightly higher quality than the API CD oil.
Engine oil consumption
Oil consumption in an internal combustion engine refers to the amount of oil consumed by the engine during operation. Oil consumption should not be understood as the amount that flows out through leaks in the joints (those. leaks).
Engine oil is consumed by the combustion of fuel in the cylinders (a small amount) and is carried away with the products of combustion and wear. Oil is also consumed as a result of high temperature and pressure in the engine. Oil consumption is affected by the operating conditions of the car, as well as the wear of engine parts. Under normal operating conditions, oil consumption is so negligible that either one small top-up or no top-up is required between two oil changes.
Oil must be added if its level is lower than specified in the specification.
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