The need to warm up the internal combustion engine has been one of the most controversial issues in the automotive community for decades. Owners of old VAZ modern BMW They often argue to the point of hoarseness, giving diametrically opposed arguments. Some say that the engine is ready to move immediately after start-up, others are convinced that without 10-15 minutes of idling, the car will die.
Truth, as is often the case, is not hidden in extremes, but in an understanding of the physical processes within. unit. Cold start is stressful for any mechanics, but the degree of this stress depends on many factors: from the viscosity of the oil to the design features. piston-group. It is important not just to follow the precepts of your grandfather, but to understand what exactly happens to your car on a frosty morning.
In this article, we will analyze the technical aspects, dispel popular myths and formulate clear rules of operation. You will understand why manufacturers are changing the guidelines and how to extend the life of their “iron horse” without unnecessary time and fuel.
Physics of cold start and heat gaps
Any internal combustion engine is designed to operate at a specific temperature, usually around 90 degrees Celsius. At this temperature, all metal parts expand to their design sizes, providing ideal heat-gaps. When the motor cools, the metal shrinks and the gaps increase, leading to knocking and increased noise on the first start.
However, the most critical thing here is not the expansion of the pistons, but the state of the engine oil. At low temperatures, the lubricating liquid thickens, turning into jelly. The pump takes time to pump thick oil throughout the system and create the necessary pressure. First seconds after launch friction between parts is maximum, since the protective film has not yet been formed.
If you start moving immediately, the load on crankshaft and camshaft It's increasing many times over. The oil does not have time to get to the most remote points of lubrication, which can lead to the formation of bullies on the surface of the cylinders. That is why short-term work at idle turns is necessary for the primary circulation of the lubricant.
⚠️ Warm up on the spot (more than 5-7 minutes) can lead to the formation of soot on spark plugs and valves, since the mixture during cold start is artificially enriched and does not burn completely.
Modern materials such as alusil alloys and special pistons coatings have a very low coefficient of thermal expansion. This means that the gaps in modern engines Toyota or Ford They don’t change as drastically as in the cast-iron blocks of old trucks. However, physics cannot be ignored: the oil must become thinner to work effectively.
Impact of heating on engine life and ecology
There is a strong opinion that the heating of the engine harms the environment. And this is partly true: at idle speeds, the catalytic converter does not reach the operating temperature, and emissions of harmful substances are maximum. However, the engine life is often more important than abstract environmental standards, although balancing is necessary wisely.
The main wear of the engine, according to various estimates, falls on the cold start mode and the first kilometers of the way. If you do not allow the oil to warm up and start gasping aggressively, you can easily damage it. liners Or call for rings to be coked. This is especially true for turbocharged engines, where the turbine bearings require high-quality lubrication under high pressure.
The environmental aspect cannot be completely ignored. Modern norms Euro-5 and Euro-6 It requires rapid heating of the catalyst. When idling, this process is slow. Therefore, the best solution is a compromise: a short warm-up for oil circulation, and then movement in a gentle mode, which allows you to warm up the exhaust system faster.
The table below compares the impact of different heating modes on key parameters:
| Warm-up mode | Engine wear and tear | Fuel consumption | Warming up the catalyst |
|---|---|---|---|
| Idle (10+ min) | Minimum | High-pitched | Very slow. |
| Right on the way. | High-pitched | Medium. | Fast. |
| Short warm-up + gentle driving | Low. | Optimal. | Normal. |
| Aggressive cold driving | critical | High-pitched | Quick, but at risk. |
Differences in heating of gasoline and diesel engines
Diesel engines have a completely different thermodynamics of work compared to gasoline analogues. The efficiency of diesel is much higher, which means that it emits less heat idle. It is almost impossible to warm up a diesel at idle speeds in winter - it will work indefinitely, remaining cold.
In addition, fuel temperature is critical for diesel engines. Solarium at low temperatures parafinized, clogging filters. Work on singles does not contribute to rapid heating of the fuel line and tank. Here the rule is relevant: started - went, but very carefully, without giving large loads.
For diesel cars in winter, the presence of a preheater (Webasto or electric) is critically important. This solves 90% of problems with cold start and engine life.
Gasoline engines, especially atmospheric, warm up faster even on idle ones. But they have a limit. Long-term operation at low speeds without load is harmful to the ignition and intake system. Nagara throttle valve EGR (exhaust gas recirculation) are frequent companions of lovers of long warming up.
Turbocharged gasoline engines require a special approach. The turbine spins up to huge speeds instantly. If the oil is thick, the lubrication of the turbocharger bearing is broken. Therefore, for turbo engines, a pause after starting is mandatory, but it should not be excessively long.
Algorithm of proper warming up in winter
The ideal winter driving algorithm looks like a sequence of clear steps. It allows you to minimize wear and save time. You don’t have to reinvent the wheel, you just have to follow the logic of physical processes.
☑️ Winter launch checklist
First, you need to prepare the car visually: clean the glass, headlights and, importantly, the roof from snow. Flying from the roof of the snow layer can slap the windshield at the most inopportune moment or fall on the hood, damaging the LCP. Then we start the engine.
After starting, let the engine run for one to three minutes. You will hear the speeds begin to decline. It's a signal from EBOU (electronic control unit) that the oil pump pump pumped the system and the mixture began to normalize. At this point, you can buckle up, adjust the navigator or music.
⚠️ Warning: Do not try to heat the engine by periodically pressing the gas pedal. This leads to a sharp enrichment of the mixture and washing the oil film from the cylinder walls with fuel, which increases wear.
After the start of movement, the first 5-10 kilometers (or minutes 10-15) move in a gentle mode. Do not exceed 2500-3000 revolutions, avoid sharp accelerations and braking by the engine. Give the transmission (especially if it is the one that is) machine or variator) also warm up. The oil in the transmission thickens even more than in the engine.
Myths about warming up and modern technologies
There are many myths that wander from generation to generation. One of them says: “Modern cars do not need to be heated at all, the engineers have planned everything.” That's a dangerous misconception. Engineers have provided protection against instantaneous destruction, but not from accelerated wear.
Another myth: “Warming up on the spot is more harmful than driving.” This is only true if you warm up the car for 20 minutes and then drive at high speeds. If we are talking about a reasonable time, then static warming is safer for bearings than the load under thrust on thick oil.
What does the breakdown statistics say?
Analysis of requests to services shows that most problems with CPG (cylinder-piston group) occur in drivers who ignore warming up in frosts below -15 degrees or, conversely, heat the car for 30 minutes daily, burning the life of candles.
Modern injection and ignition systems really work more efficiently than carburetor predecessors. But they do not override the laws of physics. Metal is metal, butter is oil. Technology only mitigates transitions, but does not make them instantaneous.
It is also believed that a high-quality synthetic Mobil 1 or Castrol It works instantly at -30. It's not. Synthetics retain fluidity better than mineral water, but it also takes time to get to the top of the engine and create a protective layer.
Economic aspect: fuel vs repair
Many drivers refuse to warm up, wanting to save fuel. Let's do the math. For 10 minutes of warming up, a modern two-liter engine will consume about 150-200 ml of gasoline. That’s a penny compared to the cost of overhauling an engine or replacing a turbine.
The engine resource, which is regularly warmed up (reasonable time) and operated in a gentle mode, can reach 400,000-500,000 kilometers before the first serious intervention. An engine that is constantly starving in the first minutes of operation may require attention to 200,000.
The fuel costs of short heating are incomparably small compared to the potential cost of engine repairs caused by oil starvation.
In addition, a cold engine consumes more fuel when driving until it reaches operating temperature. If you start driving immediately, the first kilometers of consumption will be increased due to the enriched mixture. So the savings from not warming up can be illusory.
It is also important to consider the residual value of the car. A car with a live, non-knocking engine will always cost more in the secondary market. Buyers are more willing to take copies that were serviced wisely, rather than being exploited at the limit of possibilities from the first seconds.
Frequently Asked Questions (FAQ)
How long should I keep my car warm at 20 degrees?
The optimal time is 3-5 minutes. During this time, the oil will have time to circulate through the system, and the engine speed will fall from the starting (1200-1500) to the working blanks (800-900). There is no point in keeping it longer - the engine will cool off from the wind, and the resource will be spent.
Do I need to heat the machine box?
It is not necessary to specifically heat the box on the spot (switching the P-R-N-D selector) and even harmful for some types of boxes. DISTRIBUTION. It is enough after heating up the engine to start the movement very smoothly, without sharp starts, the first 2-3 kilometers. The oil in the box will be heated by the heat of the engine and its own circulation.
Is heating harmful to the catalyst?
Short heating (up to 3-5 minutes) does not cause critical damage to the catalyst. Harmful is the long-term work on idlers, when unburned fuel burns out already in the exhaust manifold or on the cells of the catalyst, causing them to melt. The short-term mode of operation on the enriched mixture at start-up is normally calculated by engineers.
Can the engine be warmed in the cold?
Gas equipment (HBO 4th generation) at cold start usually switches to gasoline. It is impossible to heat a cold engine on gas: the gas evaporates poorly, which leads to improper mixture and damage to rubber nozzle seals. The engine should warm up to at least 30-40 degrees before switching to gas.