The situation of gas mixed with engine oil is one of the most critical for the heart of your car. distressingBut ignoring the problem can lead to liners turning, cylinder sniffs and expensive overhauls.
In this article, we will discuss in detail why the fuel is in the crankcase, how to diagnose the malfunction yourself, and what steps to take immediately. Understanding the physics of the process will help you avoid fatal errors in the operation of the engine.
First of all, we need to understand that oil-liquefaction The oil is very thin, and the metal parts are dryly frictioned, and if you notice these signs, the car's continued operation without diagnosis is very limited.
Why gasoline is in the engine crankcase
The main reason for the fuel entering the oil system is a leakage or malfunction of the elements of the cylinder-piston group. nozzleThey pour fuel instead of spraying it with a torch, and the excess gasoline flows down the cylinder walls down into the crankcase, bypassing the combustion chamber.
Another common scenario involves frequent cold starts in winter: the electronic control unit (ECU) artificially enriches the mixture to warm up the catalyst. piston-ring It seeps into the oil. This is called oil dilution.
Mechanical damage should also be considered:
- 💧 Cracks in the cylinder block or block head connecting the fuel and lubrication channels.
- 💧 Wear of oil caps that pass fuel when the engine is stopped.
- 💧 Failure of the fuel pressure regulator, creating excessive pressure in the ramp.
⚠️ Warning: If the oil level on the probe is well above the maximum mark and there is a sharp smell of gasoline, starting the engine is strictly forbidden! this can lead to a hydraulic shock or instantaneous destruction of the sliding bearings.
It's important to understand that in today's direct injection engines (GDI, TFSI), the risk of fuel getting into the oil is higher because of the design: the fuel is fed at high pressure directly into the cylinder, and the slightest error in timing of the injection leads to "overflow".
Key symptoms and signs of mixing
Not only can you diagnose the problem in the lab, but you can also diagnose it indirectly during use, and the first and most obvious symptom is that the oil level is unstable, and if you've recently added a liter, and after a week the probe shows a maximum or the oil is squeezed through the gums, it's this. sure-fire It's a foreign liquid.
Smell is the second most important indicator. Open the hood on the warmed-up engine and sniff. If the oil-filled neck or probe smells not of the characteristic "oil ferment", but of the sharp aroma of fresh gasoline, the situation requires immediate intervention.
Pay attention to the behavior of the car:
- 🚗 The engine is noisier than usual, especially at idle speeds.
- 🚗 There is a loss of traction and an increase in fuel consumption.
- 🚗 Exhaust gases acquire a black or blue tint.
Visually examining the oil on the probe also gives a lot of information: Normal oil should be viscous and viscous. If it pours like water and drains from the probe instantly, its viscosity has dropped critically. The color may change to become lighter or more cloudy, but it depends on the type of base oil and additives.
Consequences of operating with diluted oil
Ignoring the mixing of gasoline and oil leads to a chain reaction of engine failure, and gasoline has no lubricating properties, and it is an aggressive solvent. friction-preservative from the base oil, making it useless.
The first to suffer are crankshaft bearings, and because of the low viscosity, the oil film breaks, and the metal comes into contact with the metal, causing local overheating, melting of the antifriction layer, and eventually turning the liners into a jammed engine.
Other critical implications:
- 🔥 Bullying on cylinder walls and pistons due to lack of lubrication.
- 🔥 Failure of the oil pump, which pumps a mixture of low viscosity.
- 🔥 Clogging of oil channels with wear products and lacquer deposits.
The myth of the “washing” effect of gasoline
There's a misconception that gasoline in oil helps flush the engine from the sodium, and in fact, gasoline only dissolves fresh deposits, which then precipitate and clog the oil sink's net, causing oil starvation.
The cost of repairing after such consequences is estimated in the tens of thousands of rubles. Replacing the crankshaft, the piston group and the capital weaving of the unit is what results from not replacing oil in time. The savings on diagnosis here is equal to buying a new engine.
The main danger of gasoline in oil is not the fact of mixing, but the instantaneous loss of lubricating properties, which leads to dry friction and the destruction of friction pairs in a few kilometers.
Diagnosis: how to accurately identify the problem
Before you start repairing, you need to make sure you're diagnosed, and the simplest method is a paper napkin test, put the oil from the probe on white paper, and if you have a wide, transparent halo around the drop that dries quickly and smells like fuel, then the concentration of gasoline is high.
A more accurate method is heating. Put the oil on a 100-degree-heated metal surface (like an exhaust manifold, but with caution), and if the drop starts to shoot and hiss, evaporating with cotton, it is present in it. pulp Pure oil will just slowly burn out.
For professional diagnosis, the following methods are used:
- 🔬 Laboratory analysis of oil (spectral analysis) showing the exact percentage of hydrocarbon content.
- 🔬 Measurement of compression in cylinders to eliminate problems with rings.
- 🔬 Checking the tightness of the nozzles on the stand.
Also worth checking is the ignition system. The wrong angle of ignition advance or faulty candles can cause the fuel to simply not burn and wash into the crankcase. Checking with the ECU error scanner is a must.
Step by step: oil replacement and washing
If it is confirmed that gasoline has been in the oil, the only correct solution is to completely replace the lubricant, and a partial replacement ("refreshing") is useless in this case, since the old contaminated oil will remain in the channels and on the parts.
The replacement process requires carefulness. First, drain the old oil. To do this, warm the engine to operating temperature (if safe), make the oil more fluid. Unscrew the drain plug and let the liquid drain for 15-20 minutes.
Checklist of actions during replacement:
After draining the bulk, it is recommended to remove the crankcase pallet (if the design of the car allows) and clean it of possible sludge and metal shavings. Be sure to replace the oil filter, as it is also saturated with a fuel mixture.
⚠️ Warning: Do not use aggressive chemical washes ("five minutes") if there is a suspicion of severe engine wear. They can soften old deposits that will tear off and clog the oil channels, which will lead to instant death of the engine.
After you pour the new oil, start the engine for a few minutes, then turn off and wait 10 minutes, test the level with a probe, and if the level starts to rise again or there is a smell, then the cause of the gas hit is not eliminated, and operation is prohibited.
Removing the Causes: Fuel System Repair
It's not enough to just change the oil, you have to find and fix the source of the problem. If the nozzles are faulty, you have to dismantle them and check them on the stand. Often ultrasonic cleaning and replacement of the sealing rings helps, but if the needle wears out, the nozzle needs to be replaced.
When there are problems with the ignition system (candles, coils, ignition module), the fuel does not ignite at the right time. Check the gap of the candles and the condition of the high-voltage wires. Modern cars often require the ECU to adapt after replacing the components.
Comparison of methods of solving the problem:
| Reason. | Elimination method | Complexity | Cost |
|---|---|---|---|
| Faulty candles/coils | Replacement of kit | Low. | Low. |
| Contaminated nozzles | Ultrasonic cleaning | Medium | Medium |
| Wear of piston rings | ICE overhaul | High. | High. |
| EBU error | Flashing/Adaptation | Medium | Medium |
In cases where gasoline is fed through the vacuum pressure regulator of the fuel (on older systems with a reversible), the regulator itself needs to be replaced. It is easy to check it: remove the vacuum hose - if gasoline drips from there, the part is dead.
When driving for short distances (less than 5 km) in winter, gasoline in oil is almost inevitable evil. Under such conditions, change oil 1.5-2 times more often than the regulation to avoid coking the rings.
Prevention and expert advice
To avoid a repeat of this situation, you need to rethink the way you operate a car: long idling, warming up the engine in place in the cold are the main enemies of oil; the engine of a modern car is better to warm up in motion, without high loads.
Use only quality fuels at proven gas stations. Low octane or impurities in gasoline can cause detonation and malfunction of the ECU, which indirectly leads to re-enrichment of the mixture.
Regularly monitoring oil levels is a habit that saves engines. Check the probe once a week, especially before long trips. Pay attention not only to the level, but also to the color and smell.
⚠️ Warning: Never ignore an oil pressure indicator that catches fire and you know there is gasoline in the oil, shut down the engine immediately, which is only seconds before it is damaged permanently.
Keeping the oil intervals in place is another key factor, and even if the car doesn't drive much, the oil ages over time, and in a city where the engine is heavy, it's best to reduce the replacement interval to 7,000 to 8,000 kilometers.
The best prevention is timely maintenance and avoidance of short trips on unheated engine, which are the main cause of fuel condensation in oil.
Can I drive if I smell the oil but the level is normal?
Not recommended. Even if the level is not visually changed, the properties of the oil are already broken. Viscosity has dropped, and under load (acceleration, climbing uphill), the oil film can rupture, which will lead to bullies. It is better to add fresh oil to the house or service, but not to operate the car for a long time.
How much gasoline in oil is considered critical?
The critical concentration is above 10%, and the viscosity of the oil drops significantly, but problems can start at 5% if the engine is running under high load, and laboratory analysis can show an accurate percentage, but the smell is already at 2-3%.
Will the addition of viscosity (thickener) in the oil help?
No, it's a temporary and dangerous measure. The thickener will not restore the lubricating properties of the base oil that have been destroyed by gasoline. Moreover, the thickener chemistry can conflict with the fuel, forming a sediment, the only solution is to change the oil and eliminate the cause.
Why did the smell of gasoline remain after the oil change?
Some of the fuel could have been trapped in hard-to-reach areas of the engine, on the cylinder walls, or absorbed into rubber seals, and it's also possible that the cause of the gas leak has not been eliminated, and if the smell persists after 50 to 100 kilometers and the level rises again, look for a malfunction in the nozzles or rings.