Engine Lubrication System

GENERAL INFORMATION

Engine Oil Viscosity: Viscosity is the degree of fluidity of engine oil. The fluidity of oil changes with temperature. As temperature increases, the oil becomes thinner. This affects the strength and resistance of the lubricating film. When cold, the oil becomes thicker, its fluidity decreases, and internal frictional resistance increases.

With a cold engine, the oil must be fluid enough so as not to overload the starter, and so that it reaches all lubrication points as quickly as possible during engine starting. This requires the use of engine oil whose viscosity changes as little as possible with temperature changes.

Fluidity or viscosity corresponds to the internal friction of the oil and is designated according to the SAE (Society of Automotive Engineers) system, such as SAE 30, SAE 10, etc. Higher SAE numbers indicate thicker oils, lower numbers indicate thinner oils. However, viscosity alone does not characterize the lubricating properties of the oil.

Multi-Grade Oil: Multi-grade (all-season) oils must be used for the Primera engine. Multi-grade oils have the advantage of being suitable for temperature conditions (summer/winter). Multi-grade oils are made from a base single-grade oil (e.g., 15W). Thanks to a so-called thickener, the oil remains stable when hot, so its lubricating properties are maintained under all operating conditions. The letter "W" in the SAE designation indicates the oil is suitable for winter operation.

Fuel-Efficient Oil: Fuel-efficient oils are multi-grade oils with a friction-reducing additive that can reduce fuel consumption by up to 2 percent. Fuel-efficient oils have low viscosity (e.g., 10W-30). They are based on special oils (synthetic oils). When purchasing fuel-efficient oil, make sure it is approved by NISSAN.

Engine oil 5W-20 is suitable only for very cold climate zones. Do not use it during prolonged high-speed driving. For moderate climate zones, engine oil 10W-40 or 20W-50 is recommended.

Since the application ranges of adjacent SAE grades overlap, short-term temperature fluctuations can be disregarded.

Oil Specification. In principle, only HD oils are permitted for modern engines. HD oils are additive-enhanced oils whose lubricating properties are significantly improved by the addition of various chemically active substances. These additives provide better corrosion protection and better resistance to oxidation, in particular reduced tendency to form deposits in the crankcase, improved viscosity stabilization properties, and cleaning and dispersing properties. Cleaning and dispersing additives not only reduce deposit formation in the engine, but also dissolve deposits and finely disperse and keep in suspension other contaminants in the engine, which allows all contaminants to be drained when the oil is changed.

The HD oil grade is defined by the API system (API: American Petroleum Institute). European manufacturers also follow this system.

The designation consists of two letters. The first letter identifies the application range: S – Service, intended for gasoline engines; C – Commercial, intended for diesel engines.

The second letter indicates the performance grade in alphabetical order.

The highest grades are oils meeting API specification CE for diesel engines. Warning: Engine oils that are clearly specified by the manufacturer for diesel engines are prohibited for use in both gasoline and diesel engines. In this case, the container shows a dual designation (for example, SF/CD). For the Primera with diesel engines, engine oils – SD are suitable.

Oil Consumption. Oil consumption in internal combustion engines refers to the amount of oil that is consumed as a result of the combustion process. Oil consumption should not be confused with oil leakage caused by leaks from the oil pan, cylinder head cover, etc.

Normal oil consumption occurs due to burning of small quantities of oil in the cylinders, removal of combustion products and friction particles. In addition, oil is consumed due to the high temperatures and high pressures to which it is subjected in the engine.

Oil consumption is further affected by operating conditions, driving style, and manufacturing tolerances. Oil consumption must not exceed a maximum of 1 L/1000 km.