Table of contents: Viscosity of motor oil ↓ Universal oil ↓ Easy running oil ↓ Motor oil specification ↓ Oil consumption ↓
Viscosity of motor oil
Viscosity is the degree of fluidity of motor oil. Oil fluidity changes depending on temperature. As the temperature increases, it liquefies. This affects the durability and resistance of the lubricating film. When cold, it becomes viscous, while its fluidity decreases and internal friction resistance increases.
When the engine is cold, the oil must be thin enough to avoid overloading the starter and to be able to reach all lubrication points as quickly as possible during engine starting. This requires the use of motor oil with a viscosity that changes as little as possible with temperature changes.
Flowability or viscosity is equivalent to the internal friction of the oil and is designated by the SAE system (Society of Automobile Engineers), such as SAE 30, SAE 10, etc. Large SAE numbers indicate thick oils, small numbers indicate thin oils. But viscosity does not characterize the lubricating properties of oil.
Universal oil
The Primera engine must use universal (all season) oils. All-season oils have the advantage of being adapted to temperature conditions (summer/winter)All-season oils are made on the basis of liquid single-season oil (for example, 15 W). Thanks to the so-called thickener, the oil is stabilized in a hot state, so that its lubricating properties are preserved under any operating conditions. The letter "W" in the SAE designation means that the oil is suitable for use in winter conditions.
Easy running oil
Easy-running oils are all-season oils with added friction reducing agents that can reduce fuel consumption by up to 2 percent. Easy-running oils have low viscosity (for example, 10 W-30). They are based on unusual oils (synthetic oils). When purchasing low-speed oil, make sure it is approved for use by NISSAN.
5W-20 motor oil is suitable only for very cold climate zones. Do not use for long high-speed trips. For moderate climate zones, 10W-40 or 20W-50 motor oil is recommended.
Since the application areas of adjacent SAE classes overlap, short-term temperature fluctuations can be ignored.
Motor oil specification
In principle, only HD oils are approved for modern engines. HD oils are alloyed oils, the lubricating properties of which are significantly improved by adding various chemically active substances. These additives provide better anti-corrosion protection, better resistance to oxidation phenomena, in particular a reduced tendency to form deposits in the crankcase, improved viscosity stabilization properties, cleaning and dissolving properties. Cleaning and dissolving additives not only reduce the formation of deposits in the engine, but also have the ability to dissolve deposits and finely separate and hold them and other contaminants in the engine in a suspended state, which makes it possible to drain all contaminants when changing the oil.
HD oil grade is determined by the API system (API: American Petroleum Institute). European manufacturers also adhere to this system.
The designation consists of two letters. The first letter characterizes the range of application: S – Service, intended for gasoline engines, C – Commercial, intended for diesel engines.
The second letter indicates the variety in alphabetical order.
The highest grade are oils according to API specification CE for diesel engines.
Attention! Motor oils that have a clear indication from the manufacturer about the use in diesel engines are prohibited to use in both gasoline and diesel engines. In this case, the packaging indicates a double designation (eg SF/ CD).
For Primera with diesel engines, SD motor oils are suitable.
Oil consumption
In internal combustion engines, oil consumption is understood to mean the amount of oil consumed as a result of the combustion process. Oil consumption should not be confused with oil leakage due to leaks in the oil pan, cylinder head cover, etc.
(The article was copied from here: NissanBook)
Normal oil consumption occurs due to the combustion of small amounts of oil in the cylinders, due to the removal of combustion products and particles from friction. In addition, oil is consumed due to the high temperatures and high pressures to which it is subjected in the engine.
Further, oil consumption is affected by operating conditions, driving style, and manufacturing tolerances. Oil consumption should be a maximum of 1.0 l/1000 km.