Lawn Mower Oil Change Interval

Oil Consumption Calculation Calculator

How to calculate oil change intervals based on actual fuel consumption

Many car owners do not know how much to change the oil in the engine of their car or doubt the data provided by the manufacturer on the frequency of replacement of consumables. And for good reason. Replace through every 10-15 thousand kilometers often not quite right.

Better at the same time be guided by the number of hours worked and average speed. In response to the question of how often to change the oil in the engine there are many components. Among them are the recommendations of the automaker, operating conditions of the car (heavy / light, in the city / on the highway, often / rarely used), mileage before changing the oil and general mileage, technical condition of the car and the oil used.

Also, the factors affecting the frequency of changing the oil in the engine are the number of hours, power and volume of the engine, time since the last oil change (even without taking into account the operation of the machine). Next, we will tell you in detail about how often to change the oil in the engine, as it happens, and other things that are likely to be useful to you.

What affects the frequency of replacement

Each automaker in the manual for the car provides detailed information on when to change the oil in the engine. However, the fact is that this information is not always correct. As a rule, the value of the documentation is 10. 15 thousand kilometers (in each case, the amount may vary). But in fact, several factors affect the mileage between substitutions.

10 indicators affecting engine oil change times

  1. Type of fuel (gas, gasoline, diesel) and its quality
  2. Engine volume
  3. Brand of previously filled oil (synthetic, Semy-Synt, mineral oil)
  4. Classification and type of oils used (API and longlife system)
  5. Engine oil condition
  6. Replacement Method
  7. Total engine mileage
  8. Technical condition of a car
  9. Operating Conditions and Modes
  10. Supplies Quality

The manufacturer’s instructions are not included in this list, since for him the service interval is a marketing concept.

Operating modes

First of all, the timing of changing the oil in the engine is affected car operation. Without delving into the essence of the various transient processes, it is worth mentioning two main modes – along the highway and in the city. The fact is that when a car is traveling along the highway, firstly, the mileage runs much faster, and secondly, normal engine cooling occurs. Accordingly, the load on the motor and the oil used in it is not so high. On the contrary, if the car is used in the city, then its mileage will be significantly lower, and the engine load will be higher due to the fact that it often stands at traffic lights and traffic jams with the engine turned on. Cooling will be insufficient.

In this regard, it would be more competent to calculate how long it is necessary to change the oil in the engine, relying on working hours, how it is done in freight, agricultural and water technology. We give an example. 10 thousand kilometers in urban conditions (with an average speed of 20. 25 km / h) the car will travel for 400. 500 hours. And the same 10 thousand along the highway at a speed of 100 km / h – for only 100 hours. Moreover, the operating conditions of the engine and oil on the highway are much milder.

Riding in a metropolis rightly equates to driving on rough terrain in the matter of how it destroys oil. This is especially true in the case when its level in the crankcase is below average, and even worse when it is less than the minimum level. Also remember that in summer in hot weather, a much greater load is applied to the oil due to the high temperature, including from the hot surface of roads in megacities.

Engine volume and type

What affects the oil change frequency

The more powerful the engine, the easier it is for him to survive the change in load, as well as difficult operating conditions. Accordingly, the oil will not have such a strong effect. For a powerful motor, driving along the highway at a speed of 100. 130 km / h does not have a significant load, it will be below average. With increasing speed, the load on the engine, and hence the oil, will change smoothly.

Subcompact is another matter. As a rule, they have a “short” transmission installed, that is, the gears are designed for a small speed range, and a range of operating revolutions. Accordingly, subcompact engines experience greater loads in critical conditions than powerful ones. When the load on the motor increases, the temperature of its pistons increases, as well as the amount of crankcase gases. This leads to a general increase in temperature, including oil temperature.

Particularly difficult for small displacement forced engines (for example, 1.2 TSI and others). In this case, the load is supplemented by a turbine.

Additional factors

These include the high temperature of thermostatting (operating temperature), poor ventilation of the engine crankcase (especially when driving in urban conditions), the use of poor-quality or unsuitable oil for the engine, the presence of dirt in the oil channels, a clogged oil filter, and the operating temperature range of the oil.

Also of great importance is the type of oil used – mineral, semi-synthetic or fully synthetic. You can read about each of the mentioned species separately at the provided links.

Why do I need regular oil changes?

Dashboard display

What can happen to the machine if you do not change the engine oil for a long time? To answer this question, you need to understand what functions it performs. Any oil consists of a so-called “base” and a certain amount of additives. It is they who protect the engine parts.

During the operation of the machine, and even its parking, there is a continuous chemical destruction of additives. Naturally, when driving this process is faster. At the same time, natural deposits are formed on the crankcase, oxidative processes occur with the individual components of the oil, its viscosity and even the pH level change. These facts are the answers to the question – Why change oil once a year at least.

And with a significant load, the described processes in oil occur with even greater speed. Especially at high temperatures. However, modern manufacturers are constantly improving the technology and chemical composition of their oils. Therefore, they are able to withstand pollution and high temperatures for a long time.

In many modern cars, the computer constantly monitors how long to change the engine oil. Naturally, this decision is made on the basis of an empirical technique. It is based on actual data – the average number of engine revolutions, oil and engine temperatures, the number of cold starts, high-speed operation, and so on. In addition, the program takes into account errors and technical tolerances. Therefore, the computer only reports the approximate time, when you need to change the oil in the engine.

We list the causes and consequences of an untimely replacement of engine oil:

Engine deposits

  • Sedimentation. The causes of this phenomenon lie in the process of the destruction of additives or contamination of the oil with combustion products in the crankcase. The consequences are a significant reduction in engine power, an increase in the content of toxic substances in exhaust gases, and their blackening.
  • Significant engine wear. Reasons – oils lose their properties due to changes in the composition of additives.
  • Oil viscosity increase. This can happen for the same reasons. In particular, due to oxidation or violation of the polymerization of additives due to improper selection of oil. The problems arising on the basis of this should include difficulties with the circulation of oil, significant wear of the engine and its individual elements. And the occurring oil starvation of the engine can lead to difficulties with starting on a cold, in critical cases, even engine failure.
  • Crank bush. This is due to clogging of the oil channel with a thickened composition. The smaller the cross-sectional area, the greater the loads on the connecting rod bearings. Because of this, their overheating and cranking occurs.
  • Significant turbocharger wear (if available). In particular. High risk of damage to the rotor. It occurs because the used oil has a significant effect on the compressor shaft and bearings. As a result, damage and scratches form on them. And besides, dirty oil leads to clogging of the compressor lubrication channels, which can lead to its jamming.

Video: Lawn Mower Oil Change Interval

The problems described above are inherent to cars operating in urban conditions. After all, it is she who is considered one of the most difficult for the engine. Next, we present interesting factual data that were obtained experimentally. They will help you determine the mileage through which to change the oil in the engine.

Oil Experiment Results

Specialists of the well-known automobile magazine “Behind the Wheel” conducted semi-annual studies of several types of synthetic oils under operating conditions of cars in city traffic jams (at idle speed). For this, the engines worked for 120 hours (an analogue of 10,000 kilometers on the highway) at 800 rpm without cooling. As a result, interesting facts were obtained.

The first is the viscosity of all motor oils during prolonged idling until a certain (critical) moment significantly less, than when driving "on the highway." This is due to the fact that at idle there is a pass of exhaust gases and unburned fuel into the crankcase, where all this is mixed with oil. At the same time, some (insignificant) amount of oil may appear in the fuel.

The value of the decrease in viscosity of engine oil is about 0.4. 0.6 cSt (centistokes). This value is in the range of 5. 6% of the average. That is, the viscosity is within normal limits. However, this only happens until a certain point.

Clean and Used Engine Oils

About 70. 100 hours (each oil is different, but the tendency is the same for everyone) viscosity begins to increase sharply. And much faster than when working in the “track” mode. The reasons for this are as follows. The oil is constantly in contact with products of incomplete combustion (as described above), and reaches its critical saturation. The mentioned products have a certain acidity, which is transmitted to the oil. The lack of ventilation and low turbulization of the air-fuel mixture are also affected due to the fact that the piston moves relatively slowly. Because of this, the rate of fuel combustion is below average, and the ingress of exhaust gases into the crankcase is maximum.

The widespread belief that a large amount of dirt is formed in the engine at idle has not been experimentally confirmed. However, the amount of high-temperature deposits was small, and the number of low-temperature deposits was large.

As for the wear products, their quantity is much larger for the oil operated in the “cork” mode than that which was on the “highway”. The reason for this is the low speed of the pistons, as well as the high operating temperature of the oil (lack of ventilation). As for fumes, each oil behaves in its own way. However, it can be argued that due to high operating temperatures and an increase in density, soot will also increase.

Based on the information provided, we will try to systematize the data and answer the question of how many kilometers to change the oil in the engine.

Engine oil change recommendations

Next, we dwell on the question of how often to change the oil in the engine. As mentioned above, the recommendations of automakers must be treated very skeptically. Don’t completely ignore them, but amend. If you drive a car only in the conditions of the city (according to statistics, there are a majority of such car owners), this means that the oil is operated in a difficult mode. Remember that the less oil in the crankcase, the faster it gets old. Therefore, its optimal level is slightly below the maximum mark on the indicator probe.

Lawn Mower Oil Change Interval

After how many thousands to change the engine oil?

Calculation of hours for oil change

We wrote above that it’s more competent to calculate the frequency of oil changes by hours. However, the complexity of such a method lies in the fact that it is sometimes difficult to convert kilometers to hours, and based on this information to get an answer. Let us consider in more detail two methods that allow empirically, however, it is accurate enough to calculate how much to change the synthetic (and not only) engine oil. To do this, your car must have an ECU that shows the average speed and fuel consumption for the last at least one thousand kilometers (the greater the mileage, the more accurate the calculations will be).

So, the first method (speed calculation). To do this, you need to know the average speed of your car over the past several thousand kilometers and the recommendations of the automaker on which mileage you need to change the oil. For example, the mileage before changing the oil is 15 thousand kilometers, and the average speed in the city is 29.5 km / h.

Accordingly, in order to calculate the number of hours, it is necessary to divide the distance by speed. In our case, it will be 15000 / 29.5 = 508 hours. That is, it turns out, in order to make an oil change under these conditions, it is necessary to use a composition with a resource of 508 hours. However, in reality, such oils simply do not exist today.

We offer you a table showing the types of motor oils and the corresponding values ​​of engine hours according to API (American Petroleum Institute):

Oil Compliance Resource Hours
Oil type Resource hours
Mineral 150
Semi-synthetic 250
Synthetic oils
API SJ / SL 250
API SM / SN 300.350
Polyalphaolefins 350. 400
Esters 400.450

Suppose that an SM / SN class oil is filled in a car engine, which has a working life of 350 hours. To calculate the mileage, 350 hours must be multiplied by an average speed of 29.5 km / h. As a result, we get 10325 km. As you can see, this mileage is very different from the one that the automaker offers us. And if the average speed will be 21.5 km / h (which is more typical for large cities taking into account traffic jams and downtimes), then with the same 350 hours we will get 7525 km of run! Now it becomes clear why it is necessary to divide the mileage recommended by the automaker at 1.5. 2 times.

Another calculation method is based on the amount of fuel consumed. As source data, you need to know how much fuel your passport spends on your car per 100 kilometers, and this is also the actual value. It can be taken from the same computer. Suppose that according to the passport the car “takes” 8 l / 100 km, but in fact – 10.6 l / 100 km. Mileage for replacement remains the same – 15,000 km. We derive the proportion and find out how much in theory the car must spend 15,000 km to overcome: 15,000 km 8 liters / 100 km = 1,200 liters. Now we make similar calculations for actual data: 15000 10.6 / 100 = 1590 liters.

Now we need to calculate at what distance it is necessary to spend actual oil change (that is, how much the car will drive on theoretical 1200 liters of fuel). We will use a similar proportion: 1200 liters 15000 km / 1590 liters = 11320 km.

We present for you an electronic calculator that will allow you to calculate the actual mileage before changing the oil using the following data: theoretical fuel consumption per 100 km, actual fuel consumption per 100 km, theoretical distance to oil change in kilometers:

However, the simplest and most effective verification method is a visual inspection of the condition of the oil. To do this, do not be lazy to periodically open the hood and check whether the oil is thickened or burnt. His condition can be assessed visually. If you saw that the oil drains from the dipstick like water, then this is a sure sign that the oil must be replaced. Another interesting verification method is spreading the composition on a napkin. Very liquid oil forms a large and fluid stain that tells you that it is time to change the liquid. If so, immediately go to a car service or carry out the procedure yourself.

How often to change oil in a diesel engine

As for diesel engines, the same calculation logic applies as for gasoline units. It is only necessary to take into account that the working fluid in them is subjected to a greater external influence. As a result, it is necessary to change the oil in a diesel engine a little more often. In addition, domestic diesel fuel has a high sulfur content, which adversely affects the car engine.

Regarding the indications given by the car manufacturer (especially Western manufacturers), they, like gasoline engines, must be divided by 1.5. 2 times. This applies to cars, as well as vans and small trucks.

Theoretically, the choice of oil is based on the value of the total base number (TBN). It measures the amount of active anticorrosion additives in oil and indicates the tendency of their compositions to form deposits. The higher the number, the greater the ability of the oil to neutralize acidic and aggressive products formed during oxidation. For diesel engines, TBN is in the range of 11. 14 units.

The second important number that characterizes the oil is the total acid number (TAN). It characterizes the presence in the oil of products that provoke an increase in corrosion and the wear rate of various friction pairs in the car engine.

However, before deciding how many hours to change the oil in a diesel engine, you need to deal with one nuance. In particular, is it possible to use motor oils having a low alkaline number (TBN) in countries with low-quality fuel (in particular, Russian, which contains a large amount of sulfur)? During the operation of the engine, and, accordingly, of the oil, the alkaline number drops, and the acid increases. Therefore, it is logical to assume. That the intersection of their schedules at a certain mileage of the car tells us that the oil has completely exhausted its resource, and further its operation only destroys the engine. We present you the test graphs of four types of oils with different indicators of acid and alkaline numbers. For the experiment, four types of oils were taken with the conditional names of the letters of the English alphabet:

  • Oil A – 5W30 (TBN 6.5);
  • B oil – 5W30 (TBN 9.3);
  • C oil – 10W30 (TBN 12);
  • D oil – 5W30 (TBN 9.2).

As can be seen from the graph, the test results were as follows:

  • Oil A – 5W30 (TBN 6.5) – was completely exhausted after 7000 km;
  • Oil B – 5W30 (TBN 9.3) – was completely exhausted after 11500 km;
  • C oil – 10W30 (TBN 12) – was completely exhausted after 18,000 km;
  • D oil – 5W30 (TBN 9.2) – was completely exhausted after 11500 km.

That is, the most resistant was the oil for heavily loaded diesel engines. What conclusions can be drawn based on the information given:

  1. A high alkaline number (TBN) value is critical for those regions where poor quality diesel fuel is sold (in particular, with large S impurities). The use of such oil will provide you with a longer and safer operation of the engine.
  2. If you are confident in the quality of the fuel you use, then it will be enough for you to use oils with a TBN value in the region of 11. 12.
  3. Similar reasoning holds true for gasoline engines. It is better to fill in oils with TBN = 8. 10. This will give you the opportunity to change the oil less often. If you use oil with TBN = 6. 7, then in this case, be prepared for a more frequent fluid change.

For general reasons, it is worth adding that in diesel engines it is necessary to change the oil a little more often than in gasoline ones. And you should choose it, including by the value of the total acid and alkaline numbers.


Thus, each car owner must decide for himself how much to change the oil in the engine. This must be done taking into account individual circumstances. We recommend that you use the calculation methods for hours and gasoline consumption above (including calculators). Other than that, always visually assess the condition of the oil in the crankcase. So you will significantly reduce the wear and tear of your car’s motor, which saves you from having to carry out expensive repairs. Also, when replacing, buy quality oils recommended by the manufacturer.