How often to change the oil: when and how often to change the engine oil

At one time, Za Rulem experts provided the following visual data, explaining the need to reduce the service interval when changing oil for cars that spend most of their time in big cities. Typically, the average resident of the concrete jungle travels about thirty kilometers a day, while the speed rarely exceeds 50 km/h, and travel time is measured in hours. Obviously, during the same time you can cover several hundred kilometers along the highway, so it is more logical to take into account not the mileage, but the engine hours - in such conditions the oil will not withstand the 15 thousand kilometers provided for by the company regulations. At an average speed of 50 km/h, a distance of those same 15 thousand kilometers will be equivalent to 300 hours of engine operation.

Don’t forget about the comfort of the unit’s operating mode. Every driver knows that when driving evenly along the highway at a speed of 100-120 km/h, the engine does not strain at all, and there is sufficient airflow into the crankcase. True, here you should also take into account the gear ratios in the gearbox and the main gear ratio - some models with “short” numbers can tire you out at high speeds. Now remember the traffic jam in the summer heat...

How often should you change the oil: what do car manufacturers say?

The typical factory recommendation for the frequency of oil changes in a car engine varies within the range from 13,000 to 15,000 thousand km. motor rally. However, the manufacturer does not take into account the difficult operating conditions of the vehicle. Factory recommendations are relevant if:

The car's power unit is kept perfectly clean;
Engine use is limited to medium speeds;
The motor runs without overheating.

This mode is achieved at a constant speed of no more than 50 km/h, which is ensured when driving on good quality roads over long distances.

Is it possible to deviate from the manufacturer's recommendations?

After the warranty period has expired, in most cases you can deviate from the engine oil change intervals recommended by the manufacturer. The interval is reduced in the following cases:

Off-road driving;
Operating a vehicle in dusty areas;
Increased air humidity;
Significant temperature changes and extreme heat and frost;
Frequent driving with a trailer.

To visually check the condition of the engine oil, you will need to use an oil dipstick. It allows you to control the oil level in the engine (the optimal value is between the min and max marks). You can also see from the oil residue on the dipstick that it darkens as it is used. This occurs due to contamination by fuel combustion products. You should also pay attention to the condition of the lubricating fluid - if the oil flows from the dipstick like water, then it must be promptly replaced. You can also diagnose the viscosity of the composition by the degree of spreading on the napkin - a large and liquid stain indicates a loss of viscosity. In addition, you need to check the oil for thickening and burning in the engine.

When preparing a vehicle for operation in difficult conditions, it is recommended to additionally equip the vehicle with a canister of engine oil.

Oil characteristics

Viscosity, specifications, manufacturer tolerances - all this also affects the frequency of oil changes, as well as its suitability for a particular model in principle. To increase the service life of your car, you can use oil recommended by the manufacturer itself.

If the oil turns black as a result of its operation, then this is great news - the oil cleans the engine well.

How does motor oil work?

Motor oil, in addition to the lubricating composition, also consists of a certain amount of additives that protect the elements of the power unit - during the operation of the car, while it is parked, the additives undergo continuous chemical destruction. When driving, of course, this process proceeds faster. Chemical destruction is accompanied by the formation of natural deposits on the cartel of the power unit, oxidative processes occur with individual components of the motor oil - this affects the change in viscosity and pH acidity level.

Some automakers recommend changing the oil after a certain number of months.

A serious load on the car accelerates the processes described - this is especially noticeable at high temperatures.

The oil change interval in a number of modern car models is automatically monitored by an electronic control unit. The computer takes into account the average engine speed, oil and engine temperature, number of cold starts, driving speed, etc. In this case, the program takes into account errors and technical tolerances. The computer reports the approximate time for changing the oil in the car's power unit.

The use of low-quality fuel and oils, as well as the use of counterfeit products, also affect the frequency of lubricant replacement. Experts recommend reducing the interval specified by the manufacturer by approximately one third - for example, with the recommended 10 thousand kilometers, you should start changing the oil after 7 - 7.5 thousand.

At the same time, regardless of the intensity of use of the car, the oil must be changed at least once a year - the shelf life of the composition poured into the engine ranges from 6 months to 1 year.

Fuel quality

Fuel affects the frequency of oil changes, primarily due to the possibility of sand, dirt or water being introduced into it. All this almost always happens at unverified gas stations.

Oil, in addition to chips and scale from natural use, also absorbs excess dirt, which in theory should not have been there.
This significantly reduces its service life and accelerates aging. And frequent oil changes can neutralize all the negative effects of low-quality fuel.

Consequences of untimely engine oil change

Untimely replacement of engine oil leads to the following consequences:

Deposits on the elements of the power unit - they are formed during the destruction of additives, or contamination of the oil with combustion products in the engine crankcase. Deposits lead to a serious reduction in engine power, increase the content of toxic substances in the exhaust gases and lead to their blackening;
Increased engine wear - oil loses its properties due to changes in the composition of additives;
An increase in oil viscosity - oxidation, disturbances in the polymerization of additives, resulting from improper selection of oil, lead to its thickening. Excessively viscous oil does not circulate well in the engine, which leads to wear of its individual elements and the engine as a whole. The resulting oil starvation of the engine leads to problems when starting in cold conditions, and in critical situations can lead to engine failure;
Rotation of the connecting rod bearings occurs due to clogging of the oil channel with thickened compounds. The smaller its cross-sectional area, the higher the loads exerted on the connecting rod bearings. Because of this, the elements become very hot and rotate;
Severe wear on the turbocharger (if equipped) – increases the risk of rotor damage due to excessive exposure of the compressor shaft and bearings to waste oil. Because of this, scratches and mechanical damage appear on the parts. In addition, dirty oil can clog the compressor's lubrication passages, which can cause it to seize.

When to add oil to the engine?

The question is rather rhetorical. Of course, immediately after detecting a low level. As a rule, the car owner knows what the car's lubricant consumption is. By regularly looking at the odometer, you can accurately determine the need to replenish the volume. At the same time, no one canceled regular monitoring.

If there are 1000-1500 km left before the next scheduled maintenance, there is no point in wasting fresh engine oil on topping up. Perform maintenance ahead of schedule. At the same time, you should purchase new oil with a reserve, since you know exactly how much fluid will have to be added during the service period.

What factors affect the oil change interval?

The frequency of oil changes depends on many factors - of which the manufacturer’s recommendations are far from decisive. Automaker specialists, when indicating the oil change service interval, imply ideal operating conditions for the vehicle. Real factors in the frequency of replacing the lubricant, as a rule, lead to a reduction in the interval specified by the manufacturer. So, when choosing an oil change interval, take into account:

The type of fuel used is gasoline, diesel or gas. Also its quality is key;
Power unit volume;
The type of oil previously used - synthetic, semi-synthetic or mineral;
Classification and type of oils used (API and longlife system);
Condition of the filled oil;
Replacement method;
Total mileage of the power unit;
Technical condition of the vehicle;
Quality of consumables used;
Conditions and modes of vehicle operation.

Note to drivers

Depending on what type of fuel the car runs on and what brand it is, you can use the following hint on when to change the oil:

BMW diesel 10 thousand km, petrol 12 thousand km
Mazda diesel 5 thousand km, gasoline 10 thousand km
Nissan diesel 10 thousand km, petrol 15 thousand km
Opel diesel 7.5 thousand km, petrol 15 thousand km
Toyota and petrol and diesel 10 thousand km
Lada and diesel and gasoline 14.5-15.5 thousand km
Ford diesel or gasoline 10-15 thousand km.

Vehicle operating modes

The timing of an oil change primarily depends on the operating mode of the vehicle. They can be divided into driving on the highway and in the city. In the first case, the mileage of the car runs faster, and the engine is well cooled. This leads to less load on the power unit and the oil in it. In city driving mode, the car's mileage will be less, but the load on the engine will increase, due to the fact that the car is often stopped at traffic lights and in traffic jams with the engine running. This leads to overheating of the power plant.

Driving in city conditions has a detrimental effect on engine oil, significantly reducing its service life. This is especially evident when the level of lubricating fluid in the crankcase is below average, and even worse when it is below the min mark. In hot weather, the oil is subject to increased stress due to high temperatures.

Engine size and type

Engine power also affects the oil change interval. So, the more productive the power unit, the easier it can withstand load changes and difficult operating conditions. Accordingly, the oil will also not be strongly affected. For a motor with good power, driving on the highway in the range from 100 to 130 km/h does not exert a significant load - the level of impact will be below average. Increasing the speed will lead to a smooth change in the load on the engine and oil.

As for small-displacement power plants, they are equipped with a transmission designed for a small speed range and operating speed range. Therefore, low-power motors are subject to a large load in critical driving conditions. When the engine is loaded, the temperature of its pistons increases and the amount of crankcase gases increases. This leads to heating of the power unit and an increase in the temperature of the engine oil.

Small-displacement forced engines (for example, 1.2 TSI, etc.) also “suffer” from the additional load created by the turbine.

Results of experiments with oils

Leading specialists from popular automotive publications conducted six-month experiments using several types of motor oils. The internal combustion engines were operated at idle speed for 120 hours. In this way, mileage in urban conditions was simulated until the oil was changed.

As a result of the experiment, it was found that by the end of the oil’s service life, its density was significantly lower than when using the car in mixed mode or when driving only on the highway. This is explained by the fact that when the engine operates at low speeds, a significant amount of gasoline vapor, which is an excellent solvent, breaks into the crankcase.

The acidity of the oil has also changed significantly. A decrease in the alkaline number is an inevitable process that occurs even when the engine is operated without load, but at low speeds a certain amount of exhaust gases break into the crankcase, which significantly accelerate the pathological process.

As a result of the experiment, it was also possible to identify the accumulation of a large amount of wear products. Such driving affects the aging of the engine oil, and it needs to be changed much more often than when driving on the highway.

Calculation of oil change interval based on engine hours and fuel consumption

The service interval specified by the manufacturer is in many cases not suitable for choosing when to change the engine oil - experienced motorists and experts advise you to safely divide the interval specified by the manufacturer by 1.5-2 times. For example, if 15,000 km are indicated. motor rally, then it is better to change the oil and consumables after 7500-7000 km. However, you can calculate the replacement interval not only from the odometer readings, but also using engine hours and speed calculations.

In order to find out the number of engine hours, you can use an engine hour meter - electronic or analog. The device is connected to any circuit on which voltage appears after the ignition is turned on. Hour meters are equipped with a built-in battery, which allows you to save readings in the device’s memory even when the vehicle’s on-board power supply is turned off.

The optimal engine oil change interval is from 200 to 400 operating hours in mixed operating mode, with the exception of maximum load, driving at maximum speed and at maximum revolutions.

You can also calculate engine hours without using additional equipment. To do this, you will need to know the average speed of the car over the last few thousand kilometers of the car. Also, for the calculation, you will need to take into account the car manufacturer’s recommendations at what mileage the oil will need to be changed. For example, the mileage before replacing the lubricant is 15,000 km, and the average speed in the city is 29.5 km/h. To calculate engine hours, you will need to divide the mileage by the speed, you get 508 engine hours. So, to extend the life of the engine, you need to use oil with a service life of 508 hours. However, such oils do not exist today.

The service life number of engine hours depends on the type of oil:

Mineral – 150 operating hours Semi-synthetic – 250 operating hours

For synthetic oils, the service life in engine hours is as follows:

API SJ/SL – 250 operating hours API SM/SN – 300…350 operating hours Polyalphaolefins – 350…400 operating hours Esters – 400…450 operating hours

Let’s assume that the car’s engine is filled with SM/SN class oils with a working life of 350 hours. To find out the mileage, this number must be multiplied by the average speed of 29.5 km/h, the result will be 10325 km. This mileage differs from the values specified by the car manufacturer. And at a speed of 21.5 km/h, which is typical for urban operation, the result will be 7525 km of motor mileage.

You can also calculate the optimal oil change interval based on the amount of fuel consumed. To do this, you need to know the rated fuel consumption for every 100 km/h, the actual consumption and the recommended replacement mileage - say, 15,000 km. So, for this mileage the car will nominally spend 1200 liters (1500 km * 8 l/100 km), but in fact - 1590 liters (15000 * 10.6 / 100).

Then you will need to calculate at what distance the actual oil change will be required. To do this, you will need to multiply 1200 liters by 15,000 km and then divide by 1590 liters. The total mileage will be 11,320 km, after which the oil and oil filter should be changed.

Benefits of frequent oil changes

If you change the oil every 5 thousand kilometers, then soot and carbon deposits will not form on the engine. This is a preventive measure, cleaning the engine. An additional factor will be the quality of the oil being poured.

Under no circumstances should oils of different origins (synthetic, semi-synthetic and mineral) be mixed! This will completely kill the engine.