A situation where poor-quality fuel or additives cause an engine to detonate, resembling the work of a punch, has become popularly known as "dieselite like a tractor" or "knocks like a traffic light." engine oil at traffic lightsIn fact, the term traffic light is used here as a metaphor for the rhythmic, loud thud at idle speeds that occurs when a gas is dropped or when the crankshaft is rotated at low speeds.
It's important to separate the concepts from the very beginning: if you actually put the wrong product in the tank or the crankcase, the consequences can be catastrophic. knock-off Or the thud of hydraulic compensators, which drivers associate with bad oil. Lubrication quality It plays a secondary role in the production of this sound, primarily octane fuel or wear of gas distribution units. In this article, we will discuss the real cases, the technical causes of extraneous noise and methods for solving the problem.
Many motorists, when they hear a suspicious sound, panic and look for a "magic" additive or a more viscous oil to drown out the knocking, a dangerous misconception. Change in viscosity Without addressing the root cause, it can lead to oil starvation or excessive pressure in the system, and understanding the physics of the process will help you avoid costly repairs and correctly diagnose a malfunction before the engine requires capital.
The nature of knocking: why the engine is “dieselite”
What drivers call traffic light work is technically explained by either the detonation of a fuel-air mixture or the mechanical knocking of valves. late-ignitionWhen the mixture flashes not from the spark of the candle, but from high pressure and temperature, it creates a shock wave that hits the pistons, causing a characteristic metal clang. Often this happens at low speeds under load, for example, when the car is standing in place with the gear on (in automatic transmission) or immediately after the gas discharge.
The second reason, often attributed to motor-oilIt's a thud of hydraulic compensators or valves, and if the oil is too liquid or has lost its properties because of aging, it doesn't have time to create the necessary pressure to compensate for the heat gaps, and it results in a ringing chop. Hydrocompensators They're very sensitive to the purity of the oil and its viscosity, and using low-content detergent products causes the oil feed channels to coking up, which is what makes the noise.
⚠️ Attention: Prolonged driving with signs of severe knocking ("knocking at traffic lights") can cause pistons to burn and break the ring partitions. Do not ignore this symptom, even if the car "pulls."
It is also worth mentioning the problem. potassium-ignitionIt's a phenomenon where the engine keeps running after the ignition is turned off. The red-hot particles in the combustion chamber (candle-lights, pistons edges) act as a source of ignition. In this case, the oil may have nothing to do with it, but the swelling and the formation of the charcoal make things worse. Drivers often confuse this effect with the work of a diesel engine, hence the comparison with a traffic light where the car shakes and makes noise at the idle.
The effect of oil quality on engine performance on singles
Although the main culprit of diesel knocking is often fuel, the role of the engine is not motor-oil Not only does lubricating fluid reduce friction, it also removes heat from the parts of the cylinder-piston group. If the oil loses its properties, the heat sink deteriorates, local overheating causes changes in the thermal gaps, and it is the change in the gaps that causes the very knock that drivers hear when standing at a traffic light.
The HTHS (High Temperature High Shear) is a measure of the viscosity of the oil at high temperatures and shear speeds. hydrocompensators If the oil becomes too liquid when heated, the film breaks and metal contact begins, and reviews often complain that after changing the oil to a cheaper one, the engine began to rattle.
- 🛢️ Loss of viscosity: Cheap oils can lose their properties quickly, which leads to a drop in pressure in the system and the knocking of valves.
- 🔥 Thermal instability: The low-quality base quickly oxidizes, forming lacquer deposits that interfere with the work of hydrocompensators.
- 🧼 Cleaning capacity: Lack of additives leads to the formation of sludge, clogging the mesh of the oil receiver, which causes oil starvation on singles.
It is also important to consider the compatibility of the oil with the material of the seals. Some aggressive compounds can cause the osulphur to swell or, conversely, dry out, which leads to a decrease in compression and a change in the nature of the engine. Synthetic oils The leading brands usually contain a package of additives that stabilize the engine even in extreme conditions, but they also require timely replacement.
Can I add another oil if I get caught?
In an emergency, you can add more, but only if the base base is the same (synthetics to synthetics), mixing oils from different manufacturers with different additive packages can lead to precipitation and instantaneous coking of hydraulic compensators, which will increase the knocking. It is better to have a liter of a proven brand.
Review Analysis: What Drivers Say About Other Brands
By studying forums and reviews for “motor oil at traffic lights,” there are several popular brands that are most often mentioned in the context of knocking or eliminating. semisynthetic or syntheticMany people note that after replacing the oil with a product with a higher alkaline number and a quality pack of detergent additives, the engine began to run quieter, and the effect of "dieselization" disappeared.
But there are some negative cases, and some users complain that after changing the oil to a popular brand with a label. 5W-30 The engine would start to chime on the cold, which is often because a particular worn-out engine required a more viscous film, such as a squirm. 5W-40 or 10W-40It is important to understand that the manufacturer's recommendations are a priority, but for engines with high mileage, viscosity correction is sometimes required.
The table below compares the reactions of different groups of engines to oil type changes based on aggregated feedback data:
| Type of engine | Problem. | Oil change response | The result |
|---|---|---|---|
| Atmospheric, mileage 150+ thousand km | Knocking of hydrocompensators | Transition from 5W-30 to 5W-40 | The knocking's gone down, the pressure's gone up. |
| Turbocharged, direct injection | Low-revving detonation | Brand change, fuel octane increase | The effect of the traffic lights is gone |
| Common Rail diesel | Hard work for singles | Application of oil with ACEA C3 tolerance | Work became softer, noise decreased |
| Old carburetor engine | General noise and vibrations | Transition to mineral oil 15W-40 | The throttle went down, the throttle stabilized. |
Interestingly, drivers often blame the oil for problems caused by the oil. fuel-systemFor example, contaminated injectors can give the wrong spray torch, which causes local detonation, in which case the oil change will not work, you need to conduct a comprehensive diagnosis, and the feedback confirms that where the injector was cleaned and the candles were replaced with the oil, the effect was maximum.
When choosing a used engine oil, consider the zinc and phosphorus (ZDDP) content, which creates a protective layer on parts and can reduce the noise of worn friction pairs, but excess is harmful to modern catalysts.
Fuel factor: octane number and detonation
Often, the phrase "motor oil at traffic lights" is a misinterpretation of a fuel problem. If you're filling up at an unchecked gas station and after a while you hear a ringing knock when overclocking or on idle, it's a idle. knock-offLow-octane fuels ignite ahead of time, and today's turbocharged and direct-injection engines are particularly sensitive to gasoline quality.
The electronic control unit (ECU) tries to compensate for the knock by shifting the angle of ignition ahead, but when it detonates strongly, its capabilities are limited, the driver hears a characteristic metal ringing. motor-oil It's not going to help. You need to drain poor-quality fuel or dilute it with high-octane gasoline, and you need to use special octane-corrector additives.
- ⛽ Low octane number: The main cause of detonation in gasoline engines, causing a knock of the fingers.
- 💧 Water in fuel: Getting water into the tank can cause chaotic flashes and hard work of the engine.
- 🌡️ Overheating: The high temperature of the engine reduces the detonation resistance of the fuel, provoking knocking even on normal gasoline.
There's a myth that a viscous oil can lower the temperature in the combustion chamber and remove the detonation. It's not. Oil cools parts, but it doesn't affect the temperature of the mixture's self-ignition. If you hear "diesel" after refueling, change the gas station first. Using additives to increase the octane number is a temporary measure that can save the engine on the road, but is not a panacea.
⚠️ Attention: Long-term engine detonation (the sound of a traffic light due to fuel) is guaranteed to destroy the piston group. At the first sign, reset the load and switch to neutral.
Diagnosis: how to distinguish the knock of oil from detonation
To correct the problem, you need to accurately diagnose the source of the sound. Knocking of hydrocompensators It is usually rhythmic, jamming and often depends on the engine temperature (disappears after warming up or, conversely, appears hot), Detonation sounds like a ringing, metal clanking, resembling hammer blows on an anvil, and often depends on the load and quality of fuel.
So, you can use a simple diagnostic method: open the hood on the engine running and listen. If the sound comes from the top of the cylinder head and looks like the sound of a sewing machine, it's a valve mechanism. If the sound is dead and comes from the block, accompanied by vibration, then detonation or knocking of the root liners is possible. pressure mechanical pressure gauge, as the electronic sensor can give false readings.
It's also important to pay attention to the behavior of the car in motion. If the "knock at the traffic light" disappears when dialing speed or changing gear, it's likely that the problem is vibration of the engine at certain speeds or in the cushions. If the sound is amplified under load, it's almost certainly detonation. In any case, ignoring the symptoms can lead to serious financial costs.
Remediation and prevention
If the problem is oil, the solution is to flush the engine and change the filter. flushing-oil Or soft washes that are added to the old oil before you replace it, which will help dissolve the deposits in the hydraulic compensators and oil channels, and after draining the old product, be sure to replace the oil filter with a quality one.
If the cause is detonation, the algorithm of action is different. You need to check the cooling system, because overheating is a frequent companion of detonation. You should also check the knock sensor and the lambda probe. Failure of these elements can lead to improper mixture. For prevention, use fuel additives, cleansing nozzles and combustion chambers from soda.
- 🔄 Regular replacement: Change the oil every 8-10 thousand km, without waiting for the deadline, especially when driving in the city.
- 🧹 Washing: Use engine flushing when switching to another type of oil or if replacement intervals have been exceeded.
- ⛽ Quality fuel: Refuel only at proven gas stations of large networks, avoiding dubious gas stations.
If simple methods do not help, mechanical intervention may be needed: valve adjustment (if there are no hydraulic compensators), replacement of the hydraulic compensators themselves, or even repair of the cylinder head. Major overhauls An extreme measure that can be avoided if you carefully monitor the condition of the engine and respond to changes in its “voice” in a timely manner.
The main reason for “knocking at traffic lights” is not the oil itself, but its state (pollution, loss of properties) or non-compliance of viscosity with the requirements of a worn-out engine.
Frequently Asked Questions (FAQ)
Is it true that thick oil will remove the knock of the engine?
Part of the truth is, if the knocking is caused by liner wear or increased gaps in hydraulic compensators, switching to oil with higher viscosity (e.g., 5W-30 to 5W-40) can create a denser film and reduce noise, but it is a temporary solution that does not eliminate mechanical wear.
Can a bad oil cause detonation?
The oil itself does not cause detonation, because the fuel is responsible for ignition, but the oil's carbon monoxide, its entry into the combustion chamber and the formation of soda increase the compression and temperature, which indirectly provokes detonation, and overheating due to poor heat transfer of the oil can contribute to this effect.
How often should you change the oil to avoid problems?
In urban cycles (traffic lights, traffic jams), oil ages faster, the optimal replacement interval is 7-8 thousand kilometers or 250 hours, and the use of quality fuel and timely replacement of the filter are also critical.
Should I use oil additives for knocking?
Specialized additives (antidyme, restorers) can temporarily reduce noise by enveloping parts and restoring the elasticity of the oss, but they are not a substitute for repair. If the knock is strong, the additives will only delay the inevitable.