The problem of lubricant boiling inside the internal combustion engine is quite common and usually occurs in the spring and summer, when excessive heat can provoke an additional increase in temperature inside the power plant. However, this disease cannot be ruled out even in severe frost conditions. Let's talk today about what boiling point is set for motor oil, what can cause the liquid to boil and what consequences its combustion can lead to.
Operating oil temperature and “positive” deviations from it
Temperature sensor
During operation of the motor unit, increased pressure and high temperature are created in its working area, which have a destructive effect on all interacting parts. In order to counteract these two dangerous factors, a protective substance is poured into the system - oil, which is designed to maintain an optimally comfortable environment in the installation. The operating temperature of oil in a car engine is 90-105 degrees Celsius. Any deviation from it - up or down - entails interruptions in the operation of the motor. If low temperatures affect engine starting and power, then with “positive” deviations the situation is more serious.
The boiling point of automobile oil characterizes the properties of each ingredient used in its composition. And it is determined by the lowest parameter. So, for example, if one of the additives has a boiling point of 180 degrees, and the other components have a boiling point of 195, then the first boiling point will be set for the motor oil.
The boiling process is accompanied by bubbling of the lubricant, its volatility and the formation of a large number of deposits that clog the interpart gaps and channels of the lubrication system.
Because Since oil, regardless of its base - mineral, semi-synthetic or synthetic, is a flammable product, its properties are also characterized by the main parameter - the flash point of the oil. Reaching a critical value causes ignition of fuel and lubricants. Despite the fact that many manufacturers of technical fluids indicate the ignition temperature in the range from 230 to 240 degrees Celsius, in real conditions it turns out to be much lower and amounts to 150-190 degrees. This is due to the fact that during the combustion of oil in the engine, additional vapors are formed, which cause early ignition of the lubricant. Thus, the actual flash point of the oil depends on the amount of steam produced as a result of its boiling.
Summarizing
The boiling point of motor oil has a significant effect on the operation of a car engine. As can be seen from the material presented above, an excessive increase in the temperature of the lubricant is a rather dangerous ailment that every motorist can encounter. You can reduce the likelihood of this problem occurring by performing timely vehicle diagnostics and using only high-quality lubricants.
Good to know: Boiling point of antifreeze
Every motorist should know that each brand of oil has its own boiling level. So the boiling point of 5w40 motor oil is +200, and the boiling point of 5w30 motor oil can reach + 207 degrees Celsius.
Symptoms of oil burning
There are four main symptoms of lubricant boiling. Among them:
- change in thermostat readings. Each car is equipped with a special indicator on the dashboard, with which the driver can always monitor the temperature of the engine lubricant. When the engine is well warmed up, the indicator needle should point to the average value (small deviations - no more than one division - are permissible in both directions). But as soon as the vehicle owner noticed that the arrow was slowly but surely creeping towards the red line, then it was time to sound the alarm - the temperature of the car oil began to rise.
- the sound of boiling. Not in all, but in many cases, when such a problem occurs, a sound characteristic of boiling oil occurs. It is impossible to confuse it with anything.
- smoke. Another symptom of a critical increase is smoke billowing from the engine compartment. Please note that its appearance can signal not only boiling oil, but also boiling coolant. In the latter case, it will be localized mainly in the area of the tank intended for filling antifreeze or antifreeze.
- black exhausts. If you did not notice the first three symptoms, or for some reason they did not form, but the oil temperature increased excessively, then the exhaust gas will begin to turn blue-black. Its intensity will increase, and it will be impossible not to notice it.
Video “Testing motor oils?”
User Denis MECHANIC tested different brands of fluids in his video and talked about the test results.
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What to do if the oil boils?
If you are stuck in a traffic jam or in a parking space and notice oil burning, turn off the engine immediately. There is no need to panic, the main thing is to stop the engine.
If smoke appears from the engine compartment while driving, stop the car as follows:
- Minimize the load on the power plant - to do this, take your foot off the gas pedal to lower the speed.
- Turn on the car heater to maximum airflow - this will remove some of the overheated air from the working area and reduce its concentration in the engine.
- If road conditions permit, coast until the vehicle comes to a complete stop. The oncoming wind will cool the engine compartment.
- As soon as the car stops, wait another 5 minutes and only then turn off the engine.
Remember! When the temperature inside the propulsion system increases, sudden braking of the vehicle should not be allowed.
Driver actions when the engine overheats
In order to avoid problems with the cooling system, you need to carefully monitor its condition and regularly carry out technical inspections. As soon as a breakdown occurs, it is necessary to carry out repairs and replace the failed parts
It is also important to constantly monitor the level and condition of antifreeze in the system. If sediment or deposits are observed, then you need to replace the coolant and flush all channels
But it may happen that the cooling system fails while driving. There is no need to panic though
It is important to follow the recommendations:
It is worth reducing the load on the car engine. Shifting the gear lever to “neutral” and moving freely until it comes to a complete stop will be the best solution. There is no need to turn off the engine. You need to turn the stove on to maximum. This is done to help the engine cool down. After stopping the car completely, you need to stop the engine, but do not turn off the ignition. It is needed for the furnace to operate. Then you should get out of the car and open the hood of the car. This will allow air to circulate better and the engine will cool faster. Now you need to wait about twenty minutes. Do not rush and unscrew the cap of the antifreeze tank, because the hot liquid may splash, which is dangerous to health. If there is a garage or maintenance service nearby, you need to get to it. It’s good if the car is towed. If the service is far away, it’s worth checking how much antifreeze is in the container. If it is not enough, then you need to add coolant to the system, but do this very carefully, because too sudden cooling can harm the system. After the engine has cooled down, you need to start it and slowly drive to a service station or garage
While driving, it is important to monitor the engine temperature sensor. If it increases, you need to turn off the engine and wait until it cools down.
It is important not to turn off the heater while driving.
Knowing at what temperature antifreeze boils is very useful. By understanding the reasons for the increase in the value on the thermometer, you can prevent breakdowns, save yourself from repair costs and reduce the risk of an accident.
Reasons for the problem
Let's look at the reasons why the engine oil temperature begins to rise:
- The main reason for the increase in the operating temperature of the protective lubricant is its low quality. If you are trying to save money on the maintenance of your vehicle, immediately prepare for unpleasant surprises in its operation. Low-quality motor oil cannot cope with constant temperature fluctuations inside the power plant: it quickly loses its performance properties, turning into a watery liquid, which not only begins to rapidly drain from the mechanisms, leaving them without protection, but also begins to burn and evaporate.
A similar situation occurs with a high-quality lubricant after it has become obsolete.
If the car owner neglects to change the oil, the oil product can also cause an increase in temperature inside the engine system.
- Faults in the cooling system can also cause the oil temperature to rise sharply. For example, this can be caused by a break or loosening of the fan drive belt or cooling system pump, a malfunction of the fan drive fluid coupling, contamination of the radiator and other design imperfections.
These are the two main reasons that can cause oil to boil inside the power plant.
How to warm
This would seem to be a short recommendation - on cars with AMG engines, it is not recommended to enter power modes until the oil temperature reaches 20 °C. We are talking specifically about warming up while driving. On AMG cars this is quite simple - the oil temperature is reflected in the standard menu of the on-board computer. On regular models there is no such indication. Well, okay – that’s not the point. From the factory's recommendations, we know that only oils with 0W-40 or 5W-40 ratings are allowed in AMG engines. Oil viscosity at 20 °C is not specified anywhere, but it is approximately 200...300 cSt for 0W-40 or 5W-40 oils. Those. we know that with a viscosity of 200...300 cSt, we have every right to load the motor to its fullest without fear of damage or destruction. Another thing is that such viscosity is achieved for other oils at completely different temperatures. Since the temperature change curves for viscosity vary greatly from oil to oil, we will make the following assumption:
- XW-30 oils allow you to switch to driving mode with high loads at an oil temperature of 10...15 °C;
- XW-50 oils will have to be heated to 30 degrees, and “sixties” – to 40 °C.
It’s good for AMG owners - you can catch this moment quite accurately. What should ordinary people do in “civilian” Mercedes? After all, the oil temperature is not equal to the coolant temperature! The solution is to heat the engine with a “reserve” – up to 40 degrees (coolant temperature). This is usually the beginning of the temperature gauge scale. Those. the arrow or bar has become above the 40 mark - you can “stomp it down”.
So, we know three reference points of our graph of engine oil heating modes:
The minimum engine oil temperature point at which safe starting is possible; The point at which the engine can be brought to power modes without fear of damage. It is clear that we are talking about the second phase of warming up - warming up in motion. The point is that this phase is also divided into two parts - in the first part we “sick”, not raising the speed above 2000-2500 until the oil temperature reaches 20 °C. In the second part of the warm-up while moving, we can afford to add gas and even overtake the tram; Well, a point that is more or less clear to everyone is the normal operating temperature regime, when the oil temperature is equal to or slightly higher than the engine warmed up to operating temperature; It remains to find the fourth point. This is the temperature that the oil must be brought to before warming up the oil while driving can begin. Theoretically, this value can be found, calculated, logically assumed
But for this you will need to create a complex calculation methodology that will take into account the oil temperature at start-up, the type of engine - diesel or gasoline, if gasoline - then with or without supercharging, with injection into the intake manifold or direct injection, thermostat characteristics, cylinder block material , true viscosity characteristics of the oil and much more. Okay, well, let’s even deduce a hypothetical temperature zone up to which warming up should take place while the car is stationary, and after which – while in motion. But with the exception of AMG models, not a single Mercedes has an engine oil temperature indicator
And comparing it with the coolant temperature means introducing an additional error
But with the exception of AMG models, not a single Mercedes has an engine oil temperature indicator. And comparing it with the coolant temperature means introducing an additional error.
This is where two polar points of view appear: the first - you can’t heat it up, the starting speed has dropped - and let’s go; the second is to warm it up at idle speed at least until the coolant gauge needle comes off the stop; some warm it up to operating temperature.
Why is high temperature dangerous?
If the temperature of the oil material rises above 105 degrees Celsius, then its viscosity quickly decreases, and the parts begin to come into contact with each other due to a damaged protective layer. As soon as this happens, the friction force inside the power structure will increase, which will cause a reduction in the thermal gap between the elements. Increasing the temperature of the engine oil activates its oxidation and rapid aging.
Deposits on the oil intake
The circulation of spoiled lubricant in the engine leaves particles of sludge, varnish and carbon deposits on all components of the structure. Due to oil combustion, the amount of harmful deposits increases significantly.
Carbon deposits form on the surfaces of parts as a result of carbon oxidation and are an accumulation of solids. Among them are lead, iron and other metal particles. In large quantities, carbon deposits provoke engine friction, glow ignition, and can even cause a detonation explosion.
As a result of oxidative reactions in the power plant, oil films are formed - varnishes, which, under the influence of high temperatures, are baked on the moving elements of the system.
The composition of varnishes includes ash, oxygen, hydrogen and carbon. They pose the main danger to pistons, piston rings and grooves, as well as internal combustion engine cylinders.
As soon as the temperature of the engine oil exceeds 125 degrees, it will completely lose its former viscosity and begin to leak through leaks in the structure. Thus, the motor system will begin to experience oil starvation.
The most dangerous consequence of overheating of motor lubricant can be a fire - after which it will be impossible to restore the car.
Verification methods
Sunflower oil should not smoke. Therefore, you should not wait for bubbles to appear. Cooking requires only hot liquid, not boiling. If the temperature of the oil exceeds the permissible norms and a strong gurgling sound appears, you will need to turn off the heat and cover the container with a lid. This is required so that the liquid cools down a little.
To check whether the oil has boiled or not, you can use the following methods:
- If the saucepan has already been heated up with oil, you will need to twist the container so that the oil flows over the base. The liquid should flow slowly and quickly cover the base of the container.
- Initially, you will need to heat the saucepan well, and then pour in the oil. When the liquid begins to spread in a thin layer over the hot container, it will immediately heat up to the desired temperature. However, this method is not suitable when using a non-stick frying pan.
- You need to dip a small slice of onion or garlic into the heated liquid. If it starts to sizzle, then you can start frying. However, if smoke begins to emanate from the edge of the container, the saucepan must be removed from the heat. This indicates that the liquid is very hot.
- The surface of the hot oil should be shiny.
Example values
The boiling point of sunflower oil may vary depending on the type of product used. To know to what temperature the liquid can be heated, it is recommended that you familiarize yourself with the table below.
Boiling point of corn seed oil.
It lists all acceptable foods that can be heated:
| Oil name | Boiling point |
| Peanut based unrefined | 160 ℃ |
| Peanut based, refined | 232 ℃ |
| Mustard | 254 ℃ |
| From avocado | 270 ℃ |
| From grape seeds | 216 ℃ |
| Made from unrefined walnut | 160 ℃ |
| Made from semi-refined walnut | 204 ℃ |
| From camellia seeds | 252 ℃ |
| Castor oil | 200 ℃ |
| From the pulp of virgin coconuts | 177 ℃ |
| Refined from coconut pulp | 204 ℃ |
| From hemp fruits | 165 ℃ |
| Based on corn seeds, unrefined | 178 ℃ |
| Based on corn seeds, refined | 232 ℃ |
| Based on sesame seeds, unrefined | 177 ℃ |
| Based on sesame seeds, semi-refined | 232 ℃ |
| Based on flax seeds | 107 ℃ |
| From macadamia nut | 210 ℃ |
| From sweet almond seeds | 216 ℃ |
| Based on extra virgin olive | 160 ℃ |
| Based on virgin olive | 210 ℃ |
| Olive based, refined | 199 ℃ — 243 ℃ |
| Olive based with low acidity | 207 ℃ |
| From the pulp of oil palm fruits, diffraction | 235 ℃ |
| Sunflower seed high oleic | 160 ℃ |
| From sunflower seeds, unrefined | 107 ℃ |
| Semi-refined from sunflower seeds | 232 ℃ |
| Refined from sunflower seeds | 227 ℃ |
| Rapeseed based unrefined | 107 ℃ |
| Based on rapeseed, refined | 204 ℃ |
| From rice bran | 254 ℃ |
| Creamy | 150 ℃ |
| Soybean seed based, unrefined | 160 ℃ |
| Based on soybean seeds, semi-refined | 177 ℃ |
| Based on soybean seeds, refined | 238 ℃ |
| Cotton | 216 ℃ |
Sunflower oil may first boil, then smoke, and then begin to burn. This occurs when the temperature required for optimal heating of the product has been exceeded. To avoid such situations, you need to take precautions and also monitor the temperature of the oil fluid.
