Automobiles, Cars

Which oil is better - 5W30 or 5W40 (in winter)? The best oil for winter

Extended range of temperatures of oils 5W30 and 5W40 made them popular with Russian car owners. Why? What benefit will the engine get from this, which oil is better: 5W30 or 5W40 in winter?

Synthetics or semisynthetic

At present, there is a tendency to switch to a more extended viscosity range. The most significant steps in this direction the chemists have made with respect to the creation of synthetics, adding there all the new components. For example, the company "Mobil", which is the first who has released synthetic lubricant to the market, has been working with it and experimenting for over thirty years. A huge number of emerging competitors also do not slumber and spend huge amounts of money to create a new product with enhanced capabilities. But developers who produce synthetic narrowly specialized directions, for example, for highly loaded diesels, there are few.

In addition to "pyaterochok" - synthetics, there is a similar semisynthetics. Why not use it? Of course, you can use a liquid mineral water, add thickeners, a synthetic component with a modern set of additives - and it will be quite standard semisynthetic oil for the engine in winter for example. However, it is known that its parameters will in any case be lower in comparison with synthetics. After all, the oil base plays an extremely important role, setting the physico-chemical basis.

A well-known analogy can be traced with gasoline. There is a technology where a lot of additives are added to the low-octane gasoline A-80 in an artisan way and get AI-98. But, having worked on such fuel, the motor will soon require repair: at least it will be necessary to flush the injector and replace the spark plugs. After all, it is quite clear that high-grade gasoline of the highest quality will be obtained only through the use of appropriate technologies.

Viscosity

This characteristic is of paramount importance for a lubricating fluid. This parameter determines the maximum temperature of application of the oil. Therefore, what oil is better: 5W30 or 5W40 (winter or summer), is determined precisely by this parameter. If the index is low, the lubricant should not be too viscous to perform a cold start of the motor with a starter and pump it through the pump. In the high temperature mode, the oil, on the other hand, should not have too low a viscosity, so that it is possible to provide a constant necessary pressure level in the system and to form a friction protecting film around the parts.

So, the viscosity of the oil is divided into:

Winter . With a small viscosity, the engine will start easily, but the lubricant will not work efficiently at high temperatures.
Summer . Cold start will be problematic at temperatures below zero degrees, but with a high viscosity it will reliably and stably lubricate the motor in warm and hot weather.
All-season . When it's cold outside, the oil shows the quality of winter grease, and when it's hot, it's summer.

All-seasons are becoming more widespread, displacing the first two species, since now it is no longer necessary to change the oil every time the season changes. At the same time, they show themselves as more effective and energy-saving. An example of such a lubricant is oil 5W40 (synthetics).

Other Features

Of course, other characteristics are important for the oil: detergents, antiwear, anti-corrosion and antioxidant (additives are used for this). However, viscosity has one of the main values. A lot of modern additives increase the price. Therefore, you should always pay attention to this parameter and choose the optimal ratio of lubricant properties and future operating conditions of the engine.

The main requirement that should be followed when selecting, are the requirements imposed by the vehicle manufacturer. They are listed in the instruction manual. Usually they not only contain information on the specific properties that should be inherent in the lubricant used, but also offer specific brands of oils with recommendations to apply them. Often the manual contains Shell oil (5W40, 5W30 or other type). At the same time, if your car is already far from new, and you do not have much information about its operation, you can choose the brand for the motor or transmission yourself.

Standard 1999 SAE

What do these mysterious SAE letters mean? From English the abbreviation translates as "Society of Automobile Engineers" (Society of Automobile Engineers). This is the international standard, which must correspond to the viscosity. For example, in 1999, the requirements of the standard were as follows.

According to the kinematic viscosity of the oil, a certain season is determined. It is calculated at low speeds from twenty to one hundred degrees and separately at a hundred degrees.

Starting properties are revealed through the resistance when starting a cold motor and the possibility of obtaining revolutions. Depending on the viscosity and class, temperatures from ten to thirty-five degrees of frost and high shear rates (105s-1) are determined, that is, conditions for work in crankshaft bearings during cold start are considered.

Pumpability determines the speed of lubrication to the friction parts during cold start, as well as the possible risk of engine breakdown during cold start due to the rotation of the liners. The indicator is considered at negative temperatures from fifteen to forty degrees and at low shear rates (10s-1). Under these conditions, the lubricant spreads in the pan to the oil receiver when the cold motor starts.

Viscosity at high temperature reveals a real indicator when operating in a warm season of high-loaded motors. Thus, anti-wear characteristics, friction losses and the effect on the economy of the motor are visible. It is fixed at high shear rates (106s-1). In these conditions, crankshaft bearings operate at high temperature and load.

SAE classification

This is the SAE specification, which determines the characteristics of the oil under different conditions. Currently, there are six winter classes and five summer classes. Winter is easy to determine by the presence of the letter W ("winter", which in English means "winter"). The higher the viscosity, the greater the numerical index.

Winter viscosity is denoted by 0W, 5W, 10W, 15W, 20W. 25W.

Summer - 20, 30, 40, 50.

Consider the example of oil 5W40.

Its characteristics are as follows. Class - 5W viscosity. As you can see, it can be used in the winter, that is, it depends on this indicator how easy it will be to start the engine in the frost. So, to understand what kind of oil to fill in the winter, you need to pay attention to this particular indicator.

The number "40" reveals the summer performance, that is, the ability to operate the engine at high temperatures.

If, as in our example, there is a designation of one and the other classes (that is, engine oil 5W40, as well as 5W30), this indicates the all-season nature of its application.

How to choose a winter class

When choosing viscosity, first of all follow the instructions of the car manufacturer. If there are none, follow the general recommendations.

Selecting the best oil for winter, you need to consider the conditions under which the vehicle will be operated.

Then problems with the start-up in winter and the negative consequences for the motor (for example, rapid wear and jam at start-up, which can occur in the conditions of oil starvation) can be avoided regardless of whether the 5W30 or 5W40 for the winter you are flooded. It should be understood that when starting the engine, even if it does not occur in the case of severe frost, but with a positive mark on the thermometer, it takes time for the oil pump to pump through the lubrication system so that the fluid enters all the friction parts and channels. Until then, the engine is running in conditions of lack of oil. Therefore, friction and wear are greatly enhanced. The more lubricant can maintain fluidity in the low-temperature mode, the better protection will be provided for the motor.

How to choose all-weather

Winter properties are reflected on the left side, and summer properties are reflected on the right. So, asking yourself which oil is better - 5W30 or 5W40 - in winter, you need to pay attention only to the figure on the left, and it is the same in this case.

Therefore, it is necessary to pay attention to the difference in the summer mode and to select the appropriate option depending on the operating conditions of the vehicle.

Viscosity-temperature properties

From this index depends the provision of starting the engine without heating, free pumping oil through the system and, as a result, the stable lubrication of all rubbing parts at the maximum possible loads and ambient temperature.

Even in a temperate climate, the change in winter temperature to the largest warm-up is up to one hundred and ninety degrees. Therefore, seasonal oils need to be changed depending on the season. However, when there are all-weather (for example, engine oil 5W40 and 5W30), the problem was removed. Due to their additives they are able to exhibit the necessary properties at different temperatures. That is, with a negative value they are similar to winter oils, and at high positive - summer.

Additives

Additives do not greatly increase the viscosity at low temperature, but greatly increase - at high, when the amount of macropolymer molecules is significantly increased. In all seasons (which include lubricant 5W30 and oil 5W40), the characteristics consist in the temporary possibility of changing its viscosity, also with respect to the shear rate. As the speed decreases, it increases, and when it increases, it decreases.

Most of this property manifests itself at low temperatures, but even at high temperatures, it has good consequences for the engine: low viscosity with a cold engine facilitates descent, and with warmed-up it reduces energy loss due to friction, which saves fuel.

Low temperature

The low-temperature characteristic of the oil is opened through the pour point when the lubricant ceases to flow. This indicator is realized when the temperature is five to seven degrees below that at which fluidity was possible.

Most often, congealing occurs due to the formation of paraffins in the cooled lubricant.