What is lubricant viscosity and what is lubricant viscosity?

The viscosity of the lubricating oil changes with the change of temperature, and the degree of change is the relative ratio of the standard oil, that is, the viscosity and temperature of the oil.

Excerpted from Principles of Tribology, edited by Liu Zhenglin, Higher Education Press.

How to choose a viscosity engine oil, what is the role of oil viscosity, and why must you consider oil viscosity when choosing a motor oil? Yacco French motor oil brand to tell you below: in fact, the bottle will have the viscosity of organic oil, and it is generally in a conspicuous position, you can see at a glance, the viscosity of the oil is very simple, such as:

SAE 5W 30, some bottles will be marked with SAE, while others will be marked directly with viscosity. (as shown below).

What is motor oil viscosity?

SAE (Society of Automotive Engineers) refers to the American Society of Automotive Engineers, and the viscosity standard for motor oil formulated by it is used worldwide. The viscosity of engine oil is the most important characteristic of engine oil, which is simply the resistance of fluid flow, and the so-called viscosity and thinness of oil refer to the size of viscosity.

Oil viscosity grading.

SAE uses a viscosity classification system that classifies motor oils into high-temperature types for summer, low-temperature types for winter, and all-weather types for winter and summer. There are 6 kinds of winter oils, 4 kinds of summer oils, and 16 kinds of winter and summer general oils.

1.Winter oil.

0w, 5w, 10w, 15w, 20w, 25w, the symbol "w" represents winter, the smaller the number in front of "w", the smaller its low temperature viscosity, the better the low temperature fluidity, and the lower the applicable minimum temperature.

2.Summer oil.

20, 30, 40, 50, the higher the number, the greater its viscosity, and the higher the applicable maximum temperature.

3.Winter and summer all-purpose oil.

5W 20, 5W 30, 5W 40, 5W 50, 10W 20, 10W 30, 10W 40, 10W 50, 15W 20, 15W 30, 15W 40, 15W 50, 20W 20, 20W 30, 20W 40, 20W 50, the smaller the number representing the winter part, the larger the number representing the summer part, and the wider the temperature range it is applicable to.

Engine oil viscosity requirements.

Good low-temperature start-up: the viscosity should be small at low temperature, and the low-temperature fluidity of the oil product is good, so that the oil can flow quickly to each machine part to exert lubrication and protection performance. Most of the engine wear is caused during starting, especially the wear caused by cold starting, and only a small part of the wear is caused during operation.

The higher the viscosity, the stronger the oil film is usually stronger, the greater the viscosity, the thicker the oil film attached to the metal surface, and the oil film must be thick enough to exert lubrication and protection properties. However, the viscosity of the oil changes with temperature:

When the temperature rises, the viscosity decreases (thinning), and when the temperature drops, the viscosity increases (thickens).

Therefore, the ideal oil is a suitable choice made by having high fluidity with small viscosity at low temperature and stability with high viscosity at high temperature, combined with specific driving road conditions, engine load levels and air temperature.

Lubricating oil viscosity refers to the low-temperature fluidity and high-temperature protection of lubricating oil.

The viscosity of the lubricating oil is mostly identified by SAE and other grades, W stands for winter (winter), and the higher the number in front of it, the better the low temperature fluidity of the oil, which means that the lower the ambient temperature available for use, and the better the protection ability of the engine during cold start; The number after the "W" (after a horizontal line) is an indicator of the high temperature resistance of the engine oil, and the higher the value, the better the protection performance of the engine oil at high temperatures.

For example, 5W-40 means that it can withstand external low temperature -30 °C, and the kinematic viscosity standard is between 100 degrees Celsius.

The filling oil should be added according to the vehicle manual, and the same viscosity should be added according to the requirements, and it should not be changed.

Significant. Viscosity is an important quality indicator of lubricating oil, and if the viscosity is too small, it will accelerate the wear of the friction pair and make it easy to leak oil. The viscosity is too large, the permeability and heat dissipation are poor, the internal friction resistance is large, the overmovement is difficult, and the power consumption is large.

It must be important, and it is very important, because the viscosity of the lubricating oil must be consistent with the equipment, otherwise it will not be able to use normally!

During the use of lubricating oil, the viscosity will increase due to the formation of sludge gum. In the process of lubricating oil, under the action of high temperature and high pressure for a long time, the molecular chain of polymer hydrocarbon polymers will be broken, resulting in a decrease in viscosity, so the degree of change in viscosity is related to the quality of lubricating oil.

As for what viscosity oil is used in the engine, it is related to the climate and the working condition of the engine. For example, the temperature in the south is higher than that in the north, and the viscosity of the lubricating oil used in the same working conditions in winter and spring and autumn is slightly higher. In addition, the working temperature of the gas engine is dozens of degrees higher than the temperature of the fuel engine, in order to maintain the stability of the oil film at high temperature, the viscosity of the oil is required to be relatively higher, and the high-temperature sealing between the piston and the cylinder block of the old engine is maintained at the same time, and the gas engine lubricating oil is also required to have better viscosity and viscosity stability.

In addition, to evaluate the quality of a lubricating oil, mainly look at its viscosity stability performance, the viscosity is thicker, suitable for the old engine with a large piston block clearance, and the oil film is thinner if the viscosity is small, which is suitable for the new engine with a small piston block clearance. However, regardless of whether the viscosity is large or small, the oxidation resistance and deterioration resistance of the oil at high temperature must be good.

Summary. Hello friends, this year of this lubricating oil, it means that when the engine temperature is 90 degrees to 100 degrees, the fluidity in the engine, if the higher the number, the slower the fluidity, the lower the number behind the oil, the better the fluidity, the lubrication is about the same. It's just that he has this fluidity, and this cold start is good, and this 0w 20 is like this engine oil.

What does lubricant viscosity mean?

Hello, happy to answer your questions.

Hello friends, this year of this lubricating oil, it means that when the engine temperature is 90 degrees to 100 degrees, the fluidity in the engine, if the higher the number, the slower the fluidity, the lower the number behind the oil, the better the fluidity, the lubrication is about the same. It's just that he has this fluidity, and this cold start is good, and this 0w 20 is like this engine oil.

Lubricant viscosity.

What is the meaning.

In terms of viscosity value, it is the 0w 20 behind this oil This 20 is this fluidity, plus this viscosity value.

This means that when the temperature of the engine oil is high, the fluidity in it and this lubrication are the same. The lower the number, the better.

In general, when the temperature increases, the viscosity of the lubricating oil decreases, but the lubricating oil has a certain temperature resistance range, for example, the viscosity of the mineral CLP220 gear oil between minus 20 degrees and 70 degrees basically does not change, which can ensure the lubrication requirements. However, once the range is exceeded, the viscosity will change greatly, and more than plus or minus 15% can not meet the requirements of the equipment.

For lubricating oil, synthetic oil has better temperature resistance than mineral oil, the main reason is that the molecular chain is different, the molecular structure of Xiangshou orange is different, and the lubricating oil that has no temperature requirements has not yet appeared, and the temperature of each manufacturer is different from that of sticky diocelis oil, mainly because the base oil and formula are different.

Categories: Education Science >> Science & Technology >> Engineering Technology Science.

Analysis: Lubricant is a very important class of petroleum products, it can be said that all machines with moving parts need lubricants, otherwise they will not be able to operate normally. Lubricants include oils and greases, and here we discuss lubricants.

Classification of lubricating oils.

The ISO 3448-92 standard has been developed by the International Organization for Standardization, which divides industrial lubricants into 20 grades according to their kinematic viscosity (mm2 s) at 40 hours, while internal combustion engine oils and vehicle gear oils are still divided according to the kinematic viscosity at 100 hours and the viscosity at low temperatures. Located in the same international standard, China's industrial lubricant viscosity classification standard also adopts this viscosity classification, and adds "n" in front of the viscosity number"letters, to distinguish the old grade with a viscosity of 50.

Although there are many varieties of lubricating oil, they are all made with base oil as the main body and adding appropriate additives. Base oils can be divided into two categories: mineral oils and synthetic oils. The so-called mineral oil is a lubricating base oil prepared from the best vacuum fraction or vacuum residue as raw material, and through the process of deasphalting, dewaxing and refining according to the need, mineral oil is the main raw material for the production of various lubricating oils.

However, mineral oil sometimes does not have the properties of low temperature resistance, high temperature resistance, high vacuum, flame resistance, radiation resistance and other properties required by special occasions such as aviation, aerospace and national defense. Therefore, it is also necessary to produce some synthetic lubricants with special properties through synthesis. Synthetic lubricants include poly-olefins, silicone oils, polyethylene glycols, diesters, phosphates, silicates, aldehydes, fluorocarbons, chlorofluorocarbons, polyethers, etc.

It is customary to divide lubricating oils into the following six categories according to their use occasions for convenience:

1) Internal combustion engine lubricating oil, including gas engine oil and diesel engine oil, etc.;

2) Gear oil, which is characterized by the pressure on the parts can be as high as 600-4000MPa;

3) Electrical oil, which does not play a lubricating role in use, but plays a role in insulation;

4) Hydraulic oil is a liquid medium used to transfer energy in transmission, braking devices and shock absorbers, and it also lubricates and cools.

5) Mechanical Oil This is a lubricant used on general machinery with less harsh conditions, and its quantity is second only to engine lubricant.

6) Process oils include various metal cutting fluids, heat treatment fluids and forming fluids (steel rolling fluid, aluminum rolling fluid, etc.).

In addition, there are turbine oils, refrigeration oils, cylinder oils, compressor oils, instrument oils, vacuum pump oils, and other lubricants with specific purposes.

The determination of the kinematic viscosity of lubricating oil is to use a special instrument of glass to measure the time required for a certain amount of lubricating oil to flow through a capillary at a specified temperature to grade the lubricating oil. The higher the temperature of the same grade of lubricating oil, the lower the viscosity, which is due to the increase in temperature, the gravitational force between the molecules decreases, and generally liquids have this property.