3.3.13. Engine lubrication system
Viscosity of engine oil
Viscosity is called degree of fluidity of engine oil. The fluidity of oil changes depending on temperature. With increase in temperature it is diluted. It exerts impact on firmness and resilience of the greasing film. At cold it becomes viscous, at the same time its fluidity decreases and the internal resistance of friction increases.
At the cold engine oil has to be rather liquid not to overload a starter and that it could get in the course of start of the engine perhaps quickly to all places of lubricant. It demands use of engine oil with such viscosity which whenever possible changes a little at changes of temperature.
The fluidity or viscosity is equivalent to internal friction of oil and SAE 30, SAE 10, etc. is designated on the SAE system (Society of Automobile Engineers), such as. Large numbers of SAE have dense oils, small numbers – liquid. But viscosity does not characterize lubricant properties of oil at all.
Universal (all-weather) oils have to be applied to the Primera engine. All-weather oils have that advantage that are adapted for temperature conditions (summer / winter). All-weather oils are made on the basis of liquid one-seasonal oil (for example, 15 W). Thanks to a so-called thickener oil is stabilized in a hot state so in any service conditions its lubricant properties sozranyatsya. The letter "W" in the designation SAE means suitability of oil to operation in winter conditions.
Oil of the easy course
Oils of the easy course are understood as all-weather oils with additive of the means reducing friction coefficient which can provide decrease in fuel consumption to 2 percent. Oils of the easy course have low viscosity (for example, 10 W-30). Unusual oils (synthetic oils) are their cornerstone. Upon purchase of oil of the easy course follows be convinced of whether it is allowed for use by the NISSAN company.
Engine oil 5W-20 is suitable only for very cold climatic zones. Do not apply at long high-speed trips. For moderate climatic zones engine oil 10W-40 or 20W-50 is recommended.
As scopes of the next SAE classes are crossed, it is possible not to pay attention to short-term fluctuations of temperature.
Specification of engine oil
In principle only HD oils are resolved for modern engines. HD oils are the alloyed oils which greasing properties considerably are improved thanks to additive of various chemically aktichny substances. These additives provide the best anticorrosive protection, the best resilience to the oxidation phenomena, in particular reduction of tendency to formation of deposits in a case, the improved properties of stabilization of viscosity clearing and dissolving properties. The clearing and dissolving additives not only reduce formation of deposits in the engine, but also at the same time both their and other pollution in the engine have ability of dissolution of deposits thinly to divide and keep in suspension that provides a possibility of discharge of all pollution when changing oil.
The grade of HD oil is determined by the API system (API: American Petroleum Institute). The European manufacturers also adhere to this system.
Designation consists of two letters. The first letter characterizes application range: S-Service, is intended for petrol engines, C – Commercial, intended for diesel engines.
The second letter designates a grade in alphabetical order.
The premium oils according to the CE API specification for diesel engines are.
The engine oils having accurate instructions of the manufacturer on application in diesel engines are forbidden to be used in petrol, and in diesel engines. In this case on packing double designation is specified (for example, SF/CD).
Engine oils – SD are suitable for Primera with diesel engines.
At internal combustion engines the consumption of oil is understood as an expense of that amount of oil which is spent as a result of combustion process. It is not necessary to mix an oil consumption with the leak of oil happening because of leakage of an oil case, a cover of a head of cylinders, etc.
The normal consumption of oil happens because of combustion of its small amounts in cylinders, because of withdrawal of products of combustion and particles from friction. In addition oil is spent because of high temperatures and high pressure to which it is exposed in the engine.
Further the consumption of oil is influenced by service conditions, a driving manner, and also production admissions. The consumption of oil has to make the maximum 1,0 l / 1000 km.