Pic. 6–1. Viscosity of motor oils
General information
Cars use a pressurized engine lubrication system. Oil from the oil pan through the strainer and fine filter is supplied under pressure by the oil pump. The bypass valve in the oil pump maintains the required pressure in the engine lubrication system. If the pressure in the engine lubrication system exceeds a certain level, the bypass valve opens and part of the oil flows back into the oil pan.
Passing through the oil filter, the purified oil enters the main oil line. It has an emergency oil pressure drop sensor, which, by turning on the warning lamp in the instrument cluster, signals low oil pressure. The oil filter has a bypass valve, through which, in the event of severe contamination of the filter, crude oil enters directly into the oil line.
From the main line, oil under pressure is supplied through the channels to lubricate the main bearings of the crankshaft and then through the channels in the crankshaft to the connecting rod bearings. To cool the pistons, oil is sprayed through nozzles onto the bottom of the pistons.
Through the channels, oil is supplied to the cylinder head for lubrication of the camshaft bearings and to the hydraulic tappets.
Oil viscosity
Viscosity (pic. 6–1) characterizes the fluidity of the oil, which depends on temperature. As the temperature increases, the oil becomes more fluid. This impairs the oil's ability to adhere and resist high contact pressure. As the oil cools, it thickens, fluidity decreases, and internal friction increases. The engine must be used engine oil optimal viscosity, which depends on the design, operating mode, degree of wear, ambient temperature and other factors.
When starting a cold engine, the oil must be thin enough to not overload the engine excessively. In addition, after start-up, it should penetrate faster into all lubrication points.
Oil viscosity is expressed in conventional units - SAE viscosity grades (Society of Automotive Engineers - American Association of Automotive Engineers), for example SAE 30, SAE 10. A high SAE corresponds to a thick oil, a low SAE characterizes a thin oil.
Multigrade oils
In car engines, it is preferable to use multigrade oils. The advantage of all-season oils is that they do not need to be selected depending on the time of year. They are made from liquid oil (type 10W). When heated, this oil is stabilized by a so-called thickener, which ensures the appropriate lubricating properties of the oil at different temperatures. When using multigrade oil, modern brands with a wide temperature viscosity range should be used, for example SAE 10W-40, 15W-50.
Letter W («winter» - winter) in the SAE designation, it characterizes the suitability of the use of oil in the winter.
Oil with enhanced lubricity
Oils with enhanced lubricity are multigrade oils that, among other additives, contain substances that reduce the coefficient of friction. The use of such oils reduces fuel consumption by 2%. Special raw materials are used in their production (synthetic oils).
Viscosity grades and range of oil use
Since the ranges of use of neighboring SAE classes overlap, short-term temperature fluctuations can be ignored. Mixing oils of different viscosity grades is allowed if topping up of oil is required, and the ambient temperature no longer corresponds to the viscosity grade of the oil filled in the engine.
At air temperatures below -20°C for a long time, it is recommended to fill in SAE 5W-20 oil.
CD engine oils, which are designated by the manufacturer as diesel engine oils, are not suitable for gasoline engines. There are oils that can be used in two types of engines, in which case both designations are indicated on the oil container, for example SG / CD.
Additional additives must not be added to the oil, regardless of their type and purpose.
Engine oils
For modern engines, only HD oils with enhanced lubricating properties, improved by various additives, should be used. They improve anti-corrosion protection, the best change in viscosity, detergent and solvent action, prevent oxidation and the formation of slags. Detergent and solvent additives not only reduce the formation of residues in the engine, but at the same time they have the ability to dissolve and hold these residues and other contaminants in the engine oil in a suspended state so that they are removed with the drained oil when it is changed.
The quality of HD oils is determined by the API system (American Petroleum Institut). European manufacturers also follow this system.
Brands of oils are indicated by two letters. The first letter characterizes the scope: S (servise) designed for gasoline engines; WITH (commercial) designed for diesel engines.
The second letter identifies the brand of oil in alphabetical order.
API premium oils are SG for gasoline engines and CD for diesel engines.
Gasoline engines
A - all-weather oils with increased anti-friction properties, specification VW 500 00.
B - all-weather oils, specification VW 501 01.
– all-weather oils, specifications API–SF or SG.
Diesel engines
A - all-weather oils with enhanced anti-friction properties, specification VW 500 00 (for turbocharged diesel engines mixed with oil only, VW specification 505 00).
B - all-weather oils, specification VW 505 00 (unlimited for all diesel engines).
– all-weather oils, API–CD specification (for turbocharged diesel engines only in case of emergency for topping up).
– all-weather oils, specification VW 501 01 (for turbocharged diesel engines mixed with oil only, VW specification 505 00).
Oil consumption
Oil consumption is the amount of oil required to ensure the combustion process of the air-fuel mixture. Oil consumption does not include oil losses due to leaks in the engine lubrication system. Oil consumption is determined by the temperature and pressure during engine operation. Oil consumption is also affected by vehicle operating conditions and driving style. The maximum oil consumption is 1 liter per 1000 km of the vehicle run.
Warning: Do not flood engine oil above the mark max on the index (dipstick), as unburned oil may enter the exhaust system and damage catalytic converter.
Technical data
Oil pressure (at a temperature not lower than 80°С) at idle / at 3000 min–1, bar:
- petrol engines 2.8 l 1–2/ 3–5
- petrol engines 3.7 and 4.2 l 1–2.5/ 3–5
- diesel engines 2.5 l 0.8/ 2.0
Tightening torques, Nm
Diesel engine 2.5L
|
|
Lower pallet section to upper pallet section
|
10
|
Coolant drain pipe to sump
|
10
|
Oil drain plug
|
25
|
Coolant drain plug to pipe
|
10
|
Oil pump to cylinder block
|
22
|
Oil pressure line to oil pump
|
10
|
Pressure oil line to the upper section of the oil pan
|
10
|
Balance shaft oil line to oil pump
|
10
|
Oil line to balance shaft bracket
|
10
|
Intermediate sprocket to top section of oil pan
|
10
|
Partition to balance shaft bracket
|
10
|
Oil pump sprocket to oil pump
|
22
|
Balance shaft sprocket
|
45
|
Oil filter bracket to cylinder block
|
10
|
EGR mechanical valve to intake manifold
|
22
|
EGR pipe to transition piece
|
22
|
Recirculation pipe to the front section of the intake manifold
|
10
|
Oil supply pipe to oil filter bracket
|
10
|
Diesel engine 3.3L
|
|
Lower pallet section to upper pallet section
|
10
|
Oil drain plug
|
50
|
Hose clamp
|
2
|
The upper section of the oil pan to the cylinder block
|
14
|
Bracket for power steering pump and air conditioning compressor
|
40
|
Power steering pump to bracket
|
22
|
Coolant pipe to top section of oil pan
|
10
|
Guide tube for pointer (probe) oil level to cylinder head
|
10
|
Chain sprocket for oil pump
|
34,5
|
Chain tensioner for oil pump
|
10
|
Oil pump mounting bolts
|
30
|
Damper in the oil pan to the upper section of the oil pan
|
10
|
Oil filter bracket:
|
|
M8 – 22
|
22
|
M10 – 45
|
45
|
Oil drain plug in oil filter cap
|
10
|
Emergency oil pressure drop sensor F1 to oil filter bracket
|
25
|
2.8L petrol engine
|
|
Lower pallet section to upper pallet section
|
10
|
Oil drain plug
|
40
|
Air duct to intake manifold
|
22
|
Oil heat exchanger to the upper section of the oil pan
|
30
|
The upper section of the oil pan to the cylinder block
|
10
|
The upper section of the oil pan to the gearbox:
|
|
bolts M - 8
|
25
|
bolts M - 10
|
45
|
Oil receiver pipe to oil pump
|
10
|
Torque compensator support to oil pan upper section
|
42
|
Oil pump to cylinder block:
|
|
M6 bolts
|
10
|
bolt M20
|
30
|
Timing belt tensioner to oil pump
|
22
|
Visitor comments