The situation of gasoline being mixed with engine oil is one of the most critical to the health of the internal combustion engine. Many car owners ignore the change in the smell or viscosity of the lubricant until they encounter serious breakdowns or even jamming of the unit. Understanding the physical processes leading to this mixing allows them to diagnose the problem in time and avoid costly overhauls.
In normal operation fuel-air mixture It burns in the cylinders, and the oil stays in the crankcase, providing lubrication of rubbing parts. However, a leakage of the systems or a malfunction in the electronics can cause the liquid to be destroyed. petrol It will start to drain into the crankcase, liquefying the lubricant, which not only reduces the protective properties of the oil, but also changes its chemical composition, making it unsuitable for further use.
In this article, we will examine the mechanical and electronic causes of this malfunction, examine the symptoms that can detect the problem at an early stage, and discuss the methods of elimination. crank-and-wheeler.
The main reasons for the fuel in the crankcase
The most common cause of fluid mixing is a malfunction of the power or ignition system. nozzle (injectors) lose their tightness or pour fuel instead of spraying, excess gasoline doesn't burn and runs down the cylinder walls down into the oil pallet, often after a long parking lot or when using poor quality fuel contaminated with impurities.
Another important aspect is the operation of the ignition system. spark-plug If you have a little spark or no spark, the fuel mixture in the cylinder doesn't ignite, and then the unburned gasoline through the piston rings gets into the crankcase space, and this is especially true in high-mileage engines, where the gaps between the parts are already widened.
It is also worth mentioning the problems with engine-controlFaulty sensors, such as a throttle position sensor or a mass air flow sensor, can transmit incorrect data to an electronic control unit (ECU), which results in the computer artificially enriching the mixture by supplying more fuel than is necessary for combustion, and the excess goes into oil.
When diagnosing, always check the color and smell of the oil on the probe. The sharp smell of gasoline and a change in color to a lighter one are the first signs of a problem.
Mechanical damage is also a factor: cracks in the cylinder head or GHC gasket can create channels through which fuel can enter the lubrication system directly, and although this is less common than nozzle problems, the consequences of such a malfunction are only eliminated by serious repairs.
Effects of Operation Mode and Cold Start
There's a process called the "natural" process of getting fuel into the oil, which happens on frequent short trips. cold The control system automatically enriches the mixture for stable combustion, and if the engine does not have time to warm up to operating temperature, some of the gasoline condenses on the cylinder walls and drains into the crankcase.
In winter, this process is exacerbated, low temperatures contribute to longer warming, and the viscosity of the oil in the cold state is higher, which makes it difficult to evaporate the fuel that gets there. If you regularly take trips less than 5-7 kilometers, especially in winter, the risk of accumulation of gasoline in the oil increases significantly.
In addition, mode of operation crankcase gas recycling (PCV) plays an important role. In frequent cold starts, the crankcase ventilation system can produce condensation that mixes with fuel vapors. If the PCV valve jams in the open position, this can create excess dilution, "pulling" more fuel vapor into the lubrication system.
To minimize risks, it is recommended to make periodic long trips along the highway, allowing the engine to warm up and evaporate the accumulated moisture and light fractions of fuel from the oil. However, if the smell of gasoline is strong, no long trips will help - repairs are required.
Diagnosis: How to identify the problem
You can tell the presence of gasoline in the oil by a number of indirect and direct signs. The first and most obvious symptom is the change in oil levels. If you see on the probe that the level has risen above the maximum mark, and you haven't added oil recently, that's an alarm bell. Gasoline, when mixed with oil, increases the total volume of fluid in the crankcase.
The second sign is a change in smell. Pull out the probe and smell it. petroleum productsIf you're not familiar with the smell of the spent oil, you're already there, and the color of the oil can change, and it becomes lighter and more fluid, losing its viscosity.
Technical diagnostics includes several stages:
- 🔍 Visual inspection of spark plugs: black plaque or wet candles indicate the re-enrichment of the mixture.
- 📉 Compression Measurement: Low compression in one or more cylinders may indicate the occurrence of rings through which the fuel breaks.
- 💻 Computer diagnostics: scanning the ECU for errors on oxygen sensors, lambda probes and ignition skips.
- 🧪 Laboratory oil analysis: The most accurate method to show the percentage of fuel and the change in viscosity.
⚠️ Attention: Operating an engine with oil levels above the maximum can lead to the extrusion of the omentums and the oil entering the combustion chamber, which will cause smoke and failure of the catalyst.
Engine implications and risks
Ignoring the problem can have irreversible consequences. The main function of the oil is to create a protective film between the rubbing parts. viscosity The film becomes too thin and breaks under stress, which leads to dry friction of the metal against the metal.
The main problem is that the bearings of the crankshaft and camshaft slip, because of the low viscosity of the oil, the pressure in the lubrication system drops and the parts begin to experience oil starvation, which can lead to liners turning and bullies on the necks of the shafts, which requires expensive grinding or replacement of the crankshaft.
Can the oil be restored?
There are methods of evaporating fuel from oil by prolonged heating of the engine, but they are effective only at very low concentrations. If there is a lot of gasoline, only a complete oil change helps, but this does not eliminate the cause.
In addition, gasoline is an aggressive environment for rubber seals. Valve seals, gaskets and sealing rings can swell, lose elasticity and break down, which leads to new leaks and loss of seal1 engine as a whole.
The table below compares the specifications of normal oil and oil contaminated with fuel:
| Parameter | Normal butter | Oil with gasoline |
|---|---|---|
| Viscosity | Complies with class (e.g. 5W-40) | It is much lowered like water. |
| Flash temperature | High (>200°C) | Critically low (<100°C) |
| Smell. | Specific, buttery | Sharp, petrol-powered |
| Colour | From amber to black | Lighter, murkier. |
Methods for troubleshooting
The problem begins with a precise diagnosis, if the cause is nozzleThey must be dismantled and checked on the stand for performance and spray torch, and leaky nozzles must be replaced or professionally cleaned with the replacement of filter elements.
When ignition problems occur, replacing candles and ignition coils often resolves the issue of incomplete combustion of fuel. your carHigh-voltage wires should also be checked for breakdowns.
☑️ Action plan for the detection of gasoline in oil
If the diagnostics reveal sensor errors, you need to replace the faulty elements. Often the culprit is the throttle position sensor or the "dead" lambda probe, which corrects the mixture incorrectly, after replacing the parts, you must reset the errors and adapt the throttle.
In the case of mechanical damage, such as wear of piston rings or defects in the HBC, major engine repairs will be required, and attempts to use additives to “decoct” the rings in this case can only be effective in the very early stages of occurrence.
Prevention and expert advice
To avoid gasoline getting into the oil, it is important to monitor the quality of the fueled fuel. Low-octane gasoline or fuel with a lot of impurities can cause detonation and failures in the ignition system, which indirectly leads to a problem. gas stations.
Regular maintenance is key to a long engine life, change the spark plugs and fuel filters according to regulations, a dirty fuel filter can cause the ramp pressure to drop and the nozzles to malfunction, which will cause the mixture to become over-enriched.
Timely replacement of oil and filters allows to identify the problem at an early stage, when the engine has not yet received critical damage.
Also avoid constant driving at low speeds with high load (for example, going uphill in high gear), in such conditions, the load on the engine is high, and the combustion temperature may not be enough to completely burn the mixture, which contributes to the settling of the fuel on the walls.
⚠️ Attention: Don’t try to burn gasoline out of the oil by driving high speeds on a cold engine, and this is guaranteed to lead to oil starvation and bullying.
Frequently Asked Questions (FAQ)
Can I drive if I smell the oil in the oil?
Even short-term use can lead to the crankshaft liners turning because the oil loses its lubricating properties, and the motor must be silenced and evacuated to the service station for diagnosis.
How much gasoline is allowed in oil?
Ideally, there should be no gasoline in the oil at all, and the trace amount (less than 1-2%) that can be formed with very frequent cold starts is acceptable, but it also requires control. If the oil level has increased significantly, the fuel concentration is already critical.
Will replacing the oil without repair?
Replacing the oil will temporarily reduce the concentration of the fuel, but it will not eliminate the cause of the hit. After a short time (100 to 500 km of run), the situation will recur, and the engine will again be threatened. Repair is mandatory.
Why did the smell of gasoline come back after the oil change?
This means that the fuel or ignition system malfunctions have not been corrected, that the gasoline continues to flow into the cylinders and drain into the crankcase, and that the injectors and the engine control systems need to be thoroughly diagnosed.
Does the driving style affect this problem?
Yes, aggressive driving with sharp accelerations on a cold engine or, conversely, constant driving at low speeds can contribute to incomplete combustion of fuel and its entry into the crankcase. The engine needs operating temperatures to effectively burn the mixture.