The main parameter when choosing an engine oil is the degree of its viscosity (great definition can be found at engineswork.com). Many motorists have heard this term, met it on the labels of oil cans, but not everyone knows what the numbers and letters depicted there mean, as well as why it is necessary to use this process fluid with a certain degree of viscosity on a certain motor.
Today we will reveal the secrets of the viscosity of motor oils. First of all, let’s determine the significance of the viscosity of the oil for the engine. The engine has many parts that come into contact with each other during operation. In a “dry” engine, the work of such parts will not last long, since due to mutual friction they wear out and fail relatively quickly. Therefore, engine oil is poured into the engine – a technical liquid that covers all rubbing parts with an oil film and protects them from friction and wear. Each oil has its own degree of viscosity – that is, the state in which the oil remains sufficiently liquid to perform its main function (lubrication of the working parts of the engine).
As you know, unlike the coolant, the temperature of which is always stable during driving and is at the level of 85-90 degrees, engine oil is more susceptible to external and internal temperatures, the fluctuations of which are very significant (under some operating conditions, the oil in the engine heats up to 150 degrees).
To avoid boiling oil, which can cause damage to the engine of the machine, specialists in the manufacture of this technical fluid determine its viscosity – that is, the ability to remain in working condition when exposed to critical temperatures. For the first time, the viscosity of the oil was determined by the specialists of the American Association of Automotive Engineers (SAE). It is this abbreviation that is found on oil packages. It is followed by numbers, separated by the Latin letter W (it means the suitability of the engine oil to work at low temperatures) – for example, 10W-40.
What is 5w30?
It is a multipurpose engine oil used in automobiles. It is one of the general viscosity grades as specified by the Society of Automotive Engineers (SAE) to maintain an engine over a wide temperature range. The numbers refer to the viscosity of the oil, and “w” refers to winter. The number 5 is the cold temperature viscosity and 30 is the high-temperature viscosity. They are efficient enough to flow efficiently at low temperatures, which means the oil will thicken less in colder climates to provide sufficient engine lubrication.
It is also a multi-stage engine oil that is mainly used in vehicles with heavy engines as it can withstand high temperatures for extended periods of time without compromising engine performance. 10w30 flows efficiently at high temperatures and is one of the most common grades of oil recommended for commercial vehicles with older engines because they require a thicker oil for proper engine lubrication and engine durability. The larger the first number, the thicker it becomes when the engine is hot and the more resistant to flow.
What is 10w30?
The SAE 10W-30 specification is assigned to low-viscosity engine oils intended for operation mainly in temperate climates, without severe winter frosts. Some of the specialized “energy-saving” oils made in accordance with the ILSAC GF-5 requirements also fall into this viscosity class.
Also, a number of ROLF special oils for tractors, agricultural and construction machinery, manufactured according to specific standards, fall into this viscosity class.
Motor oil 10W-30 can have any base – mineral, semi-synthetic, fully synthetic. In this case, the introduced packages of viscosity modifiers will be seriously different: since SAE 30 oils are quite “liquid” at high temperatures, a high-quality mineral base oil ROLF can fit into the requirements with a minimum of correction, but additives will already be required to ensure the required low-temperature properties.
ROLF synthetic oils have characteristics that exceed SAE limit requirements with a margin.
Advantages and disadvantages
SAE 10W-30 oils cannot be used in engines designed for higher viscosity oils without the risk of a critical drop in oil pressure. This is especially noticeable on engines with mileage, where the oil pressure is already reduced due to the wear of the oil pump, liners and camshaft beds.
However, at the same time, the use of more viscous oils is impossible in engines designed for oils of an energy-saving class: to reduce mechanical losses in such engines, among other things, the elasticity of the piston rings is reduced. The more viscous oil can no longer be removed from the cylinder walls in sufficient volume, the consumption of waste increases noticeably.
In the northern regions, to facilitate starting and improve lubrication before the engine warms up, it is desirable to use oils with a lower low-temperature viscosity index – 5W-30.
Selection of the viscosity of the oil according to the service life of the engine
The older the car, the more rubbing pairs wear out in it – parts that come into contact with each other during the operation of the power unit, and the gaps between them increase. Accordingly, in order for these parts to continue to perform their functions, it is necessary that the oil film on their surfaces is more viscous.
That is, for engines that have reached half of their resource, it is necessary to buy oils with a higher degree of viscosity, and for new ones – with a lower one.
As a result: the selection of oil by car brand is a very serious and responsible event. The durability of engine parts and, ultimately, your safety depends on it.
There is no answer to the question “Which is better – 10w-30 or 5w-30?”. It is impossible to tell which engine oil is the best because the functionality of the oil does not exist outside of the oil-engine coupling.
Whole institutions are working to determine the correspondence between engine and oil. If you independently select automobile oil, then select in the selection tool not only the type and make of your car, but also the year of car manufacture, the type of engine and the type of gearbox, if this information is available. If you have any doubts, it is better to write an appeal to our experts, indicating the VIN code of the car.
If you live in an area where temperatures remain low year-round, then 5w30 is your best bet as it performs better in cold climates and performs better on cold starts. On the other hand, if you live in an area where temperatures are consistently high all year round, you need to use 10w30 oil because it allows the oil to flow faster and lubricates parts efficiently, increasing engine wear.
Light oil is ideal for colder climates, while heavier oil performs better in warmer climates. The oil must be thin enough to get on all components when the engine is cold, but the oil must not be too thin when the engine is hot.