Is it better to have a high or low viscosity of engine oil?

The viscosity of the engine oil should mainly refer to the maintenance manual of your own model, and do not blindly change it.

In order to pursue a lower or higher viscosity grade, some old drivers do not choose engine oil in accordance with the specifications of the vehicle manual, which often causes damage to the vehicle, and these damages may erupt after a period of accumulation, and the gains outweigh the losses.

Here are two common onesWrong view: In the winter, when the temperature is low, switch to a low-viscosity oil, and in the summer, when the temperature is high, switch to a high-viscosity oil. This doesn't do anything extra to keep your car up at all!

There is no question of whether high or low viscosity is better, because they are all specific to different objects and environments, and they are not universal, and you can choose at will.

"Old cars" belong to the category of vehicles with large mechanical gap wear and tear, and it is easy to use high speed driving. It is more appropriate to use a viscous engine oil for this kind of car. The reason for this is that highly viscous oils are able to "fill" gaps that are too large and maintain good lubrication properties on surfaces with relative mechanical movement at relatively high temperatures.

Of course, the defect is also a large viscosity and a lot of power loss.

It is recommended that you use mineral synthetic oil, which has good comprehensive properties and can take into account the contradiction between viscosity and power consumption. Of course, ** is also slightly more expensive.

1. The viscosity of the engine oil should be selected according to the engine's own situation and ambient temperature, the gap between the internal parts of the engine is small, and the oil with low viscosity (dilute) is needed, on the contrary, the high viscosity (thick) oil is needed if the gap is large. Generally speaking, when a new car is a new car, the internal parts of the engine wear are small, and the clearance is naturally small, so a lower viscosity oil is needed, while an old car needs a higher viscosity.

2. The ambient temperature is also a factor, the temperature of the engine will be higher when the temperature is high in summer, and the oil with higher viscosity is needed to ensure that the oil is not too thin. On the contrary, in winter, it is necessary to have a lower viscosity to ensure the fluidity of the oil.

The viscosity of the engine oil is not right, and the car will have a phenomenon:

1) If the viscosity of the oil is too low, the engine will show a hot car noise;

2) If the viscosity is too high, the engine will show cold car noise, high fuel consumption, unpleasant acceleration and other phenomena.

Of course, the viscosity of automobile engine oil is not as large as possible. The operating temperature, precision, clearance between friction pairs, and load are basically different for each engine design. The requirements for oil viscosity also vary, so let's be frank.

For example, when the viscosity of engine oil decreases, the thickness of the oil film becomes thinner, and the shear resistance and heat dissipation performance may differ. The probability is that the engine shake vibration is intensified, the power is attenuated, and the abnormal noise increases. For example, the design of the car originally used a 30 viscosity engine oil, but when the 20 viscosity engine oil was replaced, the oil film thickness became thinner, the shear resistance was reduced, and the operating resistance of each component was reduced.

Fuel consumption will also decrease, possibly increasing power. However, when the oil film thickness becomes thinner, the tolerance to wear decreases, the mechanical wear of the engine increases, and the proportion of oil burned increases. Stability is weakened, and noise and vibration may deteriorate.

If the engine oil is rightfully mistaken, or if a low-viscosity engine oil is used, an abnormality can occur in the engine. For example, trembling, vibrations become louder, and noise becomes louder. Of course, the viscosity of motor oil is not always better.

Increase the viscosity of the engine oil, the thickness of the oil film will become thicker, the shear resistance will increase, and the resistance will increase. However, with a high viscosity, the probability of an anomaly is much lower than that of engine oil. For example, the design of the car originally used 30 viscosity engine oil, but when the 40 viscosity engine oil is replaced, the oil film thickness becomes thicker, the shear resistance is strong, the running resistance of each component increases, the fuel consumption may also deteriorate, and the power is weakened.

However, as the thickness of the oil film increases, the abrasion resistance increases, and noise and vibration may deteriorate. However, because when driving, the gap will become larger as the age of the car increases. If you get the wrong engine oil, or use a high-viscosity engine oil, the vibration of shaking and hail will become larger, the noise will become louder, and of course a small number of engines will be abnormal, and the viscosity of the engine oil is not as large as possible.

Why does it feel like the vehicle works better after adding something with high viscosity to Yui Sui? With the addition of vehicle age, the addition of mileage, and the wear and aging of various components, the requirements for oil viscosity are added lightly, and the viscosity rises moderately, which is conducive to improving the sealing and wear resistance between various parts of the engine, which is beneficial to the car.

The right viscosity of the oil is good, not high or low, but according to the model used, choose the right viscosity according to the model, and whether the oil is good or not, mainly because the viscosity of the oil changes little at high temperatures.

0W-40 is its SAE standard viscosity value. This viscosity value first indicates that the oil is a multigrade oil, w represents winter, and the number trace in front of w does not represent the fluidity rental energy at low temperatures. The lower the value, the better the low-temperature start-up performance.

The number after w represents the stability of the oil at high temperatures (i.e., the likelihood of thinning). The higher the value, the better the stability of the oil at high temperatures.

Because the engine oil has a great impact on the performance and service life of the engine, it is necessary to choose the engine oil of the same series, the same use grade and the same viscosity grade in strict accordance with the automobile instruction manual. The recommended oil in the vehicle manual is determined based on the performance of the engine and the air temperature in the sales area, among other things. It has a certain guiding role in the selection of engine oil, and the safety factor is large.

It is also one of the prerequisites for claims during the engine warranty period. If you don't have an instruction manual, choose the appropriate oil specification according to the following method.

The following are the effects of oil viscosity:

It is difficult to start the engine at low temperatures. The oil viscosity is too large, the oil is too slow when the engine starts at low temperature, although the oil pressure is high, but the oil throughput is not much, mainly because of the high viscosity and poor pumpability of the oil, at this time it is most likely to appear temporary dry friction or semi-fluid friction, which is the main reason for engine friction.

Poor cooling. The greater the viscosity of the oil, the poor fluidity, the slower the circulation speed, and the slower the speed of taking heat away from the friction surface, so its cooling effect is poor, and it is easy to overheat the engine.

Poor cleaning effect. The viscosity of the oil is large, the oil circulation speed is slow, and the number of times it passes through the filter will be reduced, and the impurities such as metal grinding chips, carbon particles, and dust that are worn down cannot be taken away from the friction surface in time, and the cleaning effect is weakened.

The viscosity of the oil is small, and it is not easy to form an oil film of sufficient thickness on the high-temperature friction surface, and the bearing capacity of the oil film is poor, and it is easy to be destroyed under the load, so that the parts can not be lubricated normally, which will increase wear.