How does gasoline get into engine oil?

Gasoline in the engine oil

Gasoline in the oil leads to a decrease in the viscosity of the lubricant, as well as a loss of its performance characteristics. As a result of such a problem, the engine starts to start badly “on hot”, its dynamics of operation decreases and the fuel consumption of the car as a whole increases. There are many reasons why gasoline appears in the crankcase – partial failure of the gasoline pump (on carbureted engines), loss of tightness of gaskets, decreased compression and some others. It is possible to determine the exact reason why gasoline gets into the oil, even in the garage conditions. To do this, there are several proven methods.

How to understand if there is gasoline in the oil (signs)

There are ten basic signs indicating that there is gasoline in the oil of the engine.

1. Oil smells like gasoline . You can usually smell it clearly when you check the level of the lubricating fluid in the crankcase. You can smell both the dipstick and the filler port. The smell is especially good when the engine is warmed up. Often the smell is not of gasoline, but of acetone.
2. The oil level gradually rises when it has not been refilled in the crankcase. This usually does not happen abruptly, but gradually as the car is used in the long term.
3. Fuel (gasoline) consumption increases in parallel with the oil level.
4. The oil becomes more fluid. That is, it loses viscosity. You can tell just by touching it with your fingers on the dipstick. Or you can just see that oil began to flow easily from the dipstick, although this was not observed before.
5. Decrease of oil pressure . And this fact can be accompanied by a simultaneous increase in its level in the crankcase. It is explained by its dilution (it is especially actual for viscous oils).
6. Difficulties of engine starting when it is hot . It is connected with loss of viscosity of oil.
7. Loss of engine power. It is expressed in the reduction of the dynamic characteristics, as well as loss of traction (the car accelerates badly, does not pull uphill). Due to an increase in friction between the parts of the main frame.
8. Spontaneous increase of engine rpm at idle. It is typical for injector engines.
9. Occurrence of errors in the ECU memory. In particular, they are related to the formation of an enriched fuel-air mixture, ignition skips, as well as malfunctions of the lambda probe (oxygen sensor).
10. Exhaust gases acquire a more pungent, fuel-like, smell. Sometimes they take on a darker hue along with it.

Note that the last three signs may also indicate other failures in the car engine, so it is advisable to make a complete diagnosis, first of all with the help of diagnostic scanners. The problem with getting fuel in the oil is also found in diesel power units, but it is determined by the same signs, but the reasons for these two types of engines will differ.

The reasons why there is petrol in the oil

There are a lot of reasons why gasoline got into the oil, including their dependence on the type of fuel system of the engine (carburetor, injector, direct injection). Let’s consider them in order, and let’s start with the injector gasoline engine:

• Use of substandard fuel . It can damage the seals, through which, over time, the fuel will leak into the engine. In addition, the fuel-air mixture created from it can damage the surfaces of cylinders, pistons, valves.
• Use of low-quality additives . Poor-quality fuel additives can ruin the sealing gaskets. Therefore, it is necessary to approach their use with an understanding of the case and to choose correctly this or that means.
• Worn cylinder piston rings and poor compression . This usually occurs due to natural causes as a result of prolonged use of the car, or due to mechanical damage. This causes the fuel to flow directly into the crankcase where it mixes with the engine oil.
• Faulty EGR system . A malfunctioning exhaust gas recirculation system may also cause gasoline to get into the oil.
• Missing injectors . In direct injection engines (e.g. TSI), if the injectors are leaking, a small amount of gasoline will leak from them into the engine oil when the engine starts. Thus, after parking with the ignition on (when the pump creates pressure up to 130 bar), the pressure in the fuel rail contributes to the fact that gasoline enters the combustion chamber, and through the gap in the rings into the oil. The same problem (though to a lesser extent) can be in common injector engines.
• Faulty vacuum fuel regulator . If it malfunctions, part of the fuel returns to the engine and mixes with the oil through the gaps.
• Rich fuel-air mixture . The formation of a rich mixture can be caused by various reasons. On injector engines, it is due to a malfunction of sensors or injectors, and in carburetor cars simply can be incorrectly adjusted carburetor.
• Faulty ignition coil / spark plug / high-voltage wires . This results in the fact that the fuel/air mixture in a particular cylinder does not burn. The air naturally escapes and the fuel vapors remain on the cylinder walls, from where they enter the crankcase.

Consider separately the causes for carbureted engines:

• Damage to the diaphragm of the gasoline pump . This can occur due to natural causes (aging and wear) or as a result of mechanical damage. The lower part of the diaphragm is designed to protect its upper part from harmful crankcase gases. Accordingly, if one or the other layer is damaged, a situation may arise when gasoline will leak into the crankcase, mixing there with the lubricant.
• Malfunction of the needle valve . Over time, it may also become damaged and malfunction by leaking gasoline.
• Improper carburetor adjustment . This can result in gasoline overflow into the carburetor, including the formation of an enriched fuel-air mixture. And if the diaphragm is damaged, the situation is only aggravated.

How to determine if there is gasoline in the oil

Determine whether there is gasoline in the oil can any car owner during the standard procedure in the morning before starting the engine. You can do it using one of the following methods.

Check the odor

The easiest way to check for gasoline in oil is to smell the oil while checking the level with the dipstick or by unscrewing the oil filler cap. If the oil in the engine smells like gasoline it should alert you and make you do some other checks. Note that the oil may not smell like gasoline but like acetone. This depends on the quality of gasoline and oil used, the condition of the lubricant, and other reasons.

Drip Test

Often as the smell of the oil changes, it becomes more liquid, that is, it begins to drip easily from the dipstick. This is also something to pay attention to, especially if the oil was filled in quite a long time ago, for example, the mileage on it is already more than the middle of its operating life. So in addition to lubrication for smell, do a drop test to determine oil quality.

So, to do it, you just need to drop a few grams of the tested lubricant on an ordinary paper. You will not get an instant answer, because you need to leave it in a warm place for at least a couple of hours (better 12 hours). But by analyzing the spreading areas (there will be a sector with a yellowish or reddish tint on the edges of the circle), then it is very likely that gasoline is getting into the oil or not.

And to nullify the erroneous suspicion, it’s worth taking a closer look at the signs discussed above and checking for combustion.

Engine oil combustion

Many experienced motorists, in order to find out if gasoline is in the oil, suggest simply lighting the lubricant on fire. Inexperienced drivers who have never encountered such a problem often mistakenly try to simply light the oil directly on the dipstick. Such approach will not give any result, unless there is already a critical part of gasoline in oil, but it is seldom, and it will be seen by other, obvious, signs.

In fact, it is necessary to ignite oil heated in a test tube. So, for this you should take a glass tube with a narrow neck and pour a small amount of oil into it. If the tube has a flat bottom, it is better to heat it on an electric stove. If the test tube has a rounded bottom, you can take it in laboratory tongs and heat it on an open fire source (kitchen stove, candle, dry alcohol, etc.). Please note that during heating, the neck (top) of the test tube must be sealed with some kind of lid so that the gasoline does not evaporate during heating.

The ignition temperature of engine oil vapor is much higher than that of gasoline vapor, so oil vapor will not burn in the normal state. Then, after a certain amount of time, when the test samples are sufficiently heated, you must open the lid of the test tube and quickly bring a source of open flame (lighter, match). If the fumes that come out do not catch fire, then most likely there is no or negligible amount of gasoline in the oil. Accordingly, if the presence of gasoline is serious, a tongue of flame will appear at the neck of the test tube. In this case, it will be the result of gasoline vapor burning from the lubricating liquid in the tube.

When performing the tests described above, follow the safety and fire prevention regulations.

What to do when gasoline is in the oil

In case you find that there is fuel in the engine oil, the first thing to think about is diagnostics to determine the cause and change the oil itself. Do not operate the car for a long time in this mode!

The search for fuel leakage into the engine oil begins with checking the compression, sealing of the injectors and their performance. Diagnosis of injectors can be done with or without disassembly. On carburetor cars need to check the carburetor setting, less often perform the replacement of the needle mechanism and the seat assembly.

In parallel with checking the operation of the fuel system is worth unscrewing and checking the plugs. The color of soot and their condition will help to judge the ignition system operation.

What are the consequences of exploitation of a car with petrol in oil?

And what will happen if gasoline got into the oil and did not detect it in time? Can the car be operated under such conditions? We shall answer at once – it is possible to exploit, but not for a long time.

It is conditioned by the fact that fuel, getting into the crankcase, makes the lubricating fluid fluid much thinner, thus violating its operational characteristics. Decreased viscosity leads to poor lubrication of separate parts of the engine, especially during its operation at high temperatures and at high loads. Besides, gasoline levels out the effect of additives it contains.

Changing the oil composition leads to engine wear and a significant reduction in its overall life (up to overhaul).

In the most critical situations the oil in the engine can simply ignite with all the ensuing consequences!

Therefore, in order not to bring to the occurrence of such situations and to preserve the life of the engine as much as possible, it is necessary to perform diagnostics and appropriate repair measures as soon as possible.

Gasoline in the oil: why it happens, what is the danger of such a situation and how it is eliminated

Oil in the engine should be checked every week. As a result of such checks, not only a decrease in its level, but also the ingress of gasoline into the lubricating fluid will be revealed. Each of these situations is dangerous to the engine and must be corrected immediately upon detection. Today we will be interested in gasoline in oil. How does it get there and how can it harm the car? How can this situation be eliminated?

How dangerous is the ingress of gasoline?

It is necessary to understand the seriousness of the situation when gasoline gets into the oil. This will allow the driver to eliminate the dangerous situation at an early stage, preventing its transition to a neglected state. The extent of consequences directly depends on the quantity of gasoline, which has already managed to get into the lubricating fluid.

With a small amount of fuel for some time the car will work properly and even in no way “will not show discontent”. Of course, with time the negative consequences will make themselves felt, but a conscious motorist will have time to identify the problem and eliminate it before that time. A large amount of fuel in the engine lubricant is able to damage the mechanism in a short time and even put it out of operation.

It is worth examining the consequences of the presence of gasoline in the engine oil in more detail:

• disruption of the engine’s duty cycle;
• shift of the fuel correction coefficient causes periodic failure of the engine;
• reduction of driving speed;
• malfunction of the piston group;
• damage to the carburetor, which leads to complete failure of the entire mechanism.

The consequences are dealt with, but how do you know if there is a problem? There are several signs, according to which you can determine the fact of fuel ingress into the crankcase with the lubricating fluid:

• large “appetites” of the car;
• noise and knocking, coming from the piston mechanism;
• Decrease of the vehicle power, which is especially evident while overcoming a steep hill;
• high oil level and abnormal color;
• A decrease in the coolant level.

In the presence of at least one of these signs, it is worth considering the possibility of diagnosing the vehicle. This procedure will not be quick and cheap, but the subsequent repair of the engine will cost even more.

Causes of gasoline in the oil

Now is the time to examine the causes that cause gasoline to get into the oil sump. There may be several of them, but each is serious and significant.

Poor quality fuel

It is not a surprise for a Russian driver, that’s why many don’t risk to fill up at “left-hand” gas stations. But even trustworthy and reliable gas stations can fail and provide low-quality product. In addition, no one is immune from long trips, when you have to fill up at unfamiliar gas stations.

Gasoline can be mixed with a lot of additives, which reduce its quality and harm the car. The most common are benzene and toluene. Nowadays, completely new additives are appearing, the effect of which on the car is more aggressive. Gasoline with this composition will be able to end up in the oil sump much faster compared to quality fuel.

Oil, when mixed with low-quality fuel, quickly loses its performance properties. In fact, incompatible components are mixed together. Gasoline in the engine oil causes rapid failure of the fuel-distributing mechanism. To avoid such a situation, you need to choose gas stations carefully and not allow yourself to be served at dubious gas stations.

Nozzles malfunction

One of the options for why gasoline is in the engine oil, are violations in the work of injector injectors. If they do not close tightly when the engine is stopped, due to residual pressure, fuel can enter the manifold and then head for the cylinders.

The problem can be easily solved. You only need to check the tightness of the injectors. It will be necessary to supply the injectors with a liquid, which is intended for flushing them. If a leak is detected, the faulty elements will have to be replaced.

Damage in the piston system

This malfunction is the most unpleasant for every motorist. The essence of the fault may lie in the formation of deformations on the cylinder walls (cracks, chips, scratches). Also caking may form on the oil rings.

The failure is determined by measuring the compression on each cylinder. If a large deviation is detected, it is most likely a faulty cylinder. Such a situation threatens the necessity of an engine overhaul.

Some craftsmen try to restore the encrusted rings. For this purpose, special chemical preparations are used. Not always a positive result is possible, so do not hope for such a method of solving the problem.

Options for fixing the problem

It is necessary to eliminate it, and as soon as possible. There are several options for solving the problem:

1. Appealing to the service station is inevitable in the case of a neglected situation. It will not be cheap, but it is necessary.
2. At the initial stage you can do with your own forces. It will be necessary to drive a few kilometers at high speed. During this time, the gasoline will leave the crankcase, but the oil will still need to be drained immediately.

As a precaution against fuel buildup in the oil sump, you should periodically drive at high speeds for about half an hour. In this way you can remove small fuel residues from the oil at the very initial stage. This method is recommended by many foreign car manufacturers.

Now you know what to do, if the gasoline is in the engine oil. Don’t forget to check the fuel mixture, assessing not only its level, but also its color. Listen to the operation of the machine and react to changes that may indicate a problem. Expensive and lengthy engine repairs will not be threatened with this approach.