Oil viscosity
Viscosity characterizes the fluidity of the oil. Depending on the temperature, the oil tends to decrease in fluidity. As the temperature increases, the oil becomes more fluid. This worsens the oil's ability to adhere and withstand high contact pressures. When cooling, the oil thickens, fluidity decreases, and internal friction increases. Because of this property, it is necessary to use motor oil with a viscosity that changes with temperature within the smallest possible limits.
Oil fluidity is equivalent to its internal friction and is designated by SAE units (Society of Automotive Engineers), for example SAE 30, SAE 10. A high SAE value means that the oil is thick, a low value characterizes liquid oil. However, oil viscosity does not fully characterize the lubricating properties of the oil.
All-season oils
In car engines, it is preferable to use all-season oils. They are made on the basis of liquid single-season oil (type 10W). When heated, this oil is stabilized by a so-called thickener, which ensures the appropriate lubricating properties of the oil at all temperatures. When using all-season oil, grades with a wide temperature range of viscosity should be used, for example, 10W-40, 15W-50.
The letter W (winter) in the SAE designation characterizes the suitability of the oil for use in winter.
Oil with enhanced lubricating properties
Oils with increased lubricating properties are all-season oils, which, in addition to other additives, contain substances that reduce the friction coefficient, which reduces fuel consumption by 2%. Special starting components (synthetic oils) are used in their production. When buying such oil, you should pay attention to the fact that this oil is approved for use by Ford.
Motor oils
Attention! Additional additives to oil, regardless of their type and purpose, should not be added to the oil.
For modern engines, only HD oils should be used. HD oils are oils with increased lubricating properties, improved by various additives. These additives provide better anti-corrosion protection, more favorable conditions against oxidation, the least tendency to form slags, the best change in viscosity, cleaning and dissolving properties. Cleaning and dissolving additives not only reduce the formation of residues in the engine, but also have the ability to dissolve these residues and all other contaminants in the engine oil and keep them in a suspended state so that when changing the oil, these contaminants are removed along with the drained oil.
The quality of HD oils is determined by the API (American Petroleum Institute) system. European manufacturers also adhere to this system.
The oil grade is designated by two letters. The first letter characterizes the area of application: S – Service, intended for carburetor engines; C – Commercial, designed for diesel engines. The second letter determines the grade of oil in alphabetical order.
The highest grade oils according to API classification are SG for carburetor engines and CD for diesel engines.