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First of all, low crankshaft speeds cause a weak supply of oil to all moving engine parts. It is connected to the crankshaft oil pump, which is responsible for pumping oil.
For each turn, the pump pumps the same amount of oil. And since it is directly connected to the crankshaft, the amount of pumped oil will directly depend on the crankshaft speed. Note that the relatively new and well-groomed engines do not have problems with oil channels, whereas experienced cars with a mileage of more than 100-150 thousand. Km are clogged with sediments and chips. This causes a problem called oil hunger. Many will argue, they say, and that at that moment took the oil pressure sensor. He must admit a flaw. Of course, he recognizes an insufficient amount of oil in the system, but oil starvation has nothing to do with the pressure of oil, so in this case it is useless to count on a light bulb on the device.
Further simple math. We have already found out that the oil pump has a direct connection with the engine crankshaft. This means that at 1,500 rpm, the pump will have two times less oil than at 3,000 rpm. Recall that the oil is responsible not only for the direct lubrication of all parts but also for the abstraction of excess heat. So oil starvation can easily turn into unnecessary overheating. Every driver at least once per trip – even a length of only a few kilometers – makes a sharp acceleration. This happens all the time – traffic drives, or just such a driving style, or maybe you just want to kill a little “automatic”.
In the process of rapid acceleration, the electronic control unit of the engine gives the command to enter into the cylinders of the air-fuel mixture in a volume several times higher than the usual one required to maintain the set speed. The oil pump and pump are physically unable to instantly speed up their work. But in cylinders, the amount of heat already exceeds the previous value several times. This warm is not removed anywhere since there is not enough oil, which increases the one-time load on the piston group and the unit itself. Excess warm can also cause detonation, which is highly undesirable. It turns out, as always. The desire to save a little fuel affects the health of the engine. The gearbox suffers have the same way. You should not constantly keep the tachometer needle near the cut-off, of course, this extreme will also help to call the service early.