Excess fuel
In winter, warming up the engine to operating temperature takes much longer than in summer. In this position, the engine management system ensures a rich fuel mixture.
And the more modern the engine and the higher the environmental standards, the richer the mixture. Excess fuel already burns in the catalytic converter, which leads to rapid heating of the ceramic cells and effective evacuation of exhaust gases.
However, gasoline from a rich mixture condenses on the walls of the cylinders that have not yet warmed up and enters the oil through the piston rings.
With frequent cold starts and short trips, the fuel from the oil does not have time to evaporate. As a result, the level in the pan gradually rises.
In addition, such an effect can be observed by owners of cars with both gasoline and diesel engines.
Where does the water come from?
When the engine is switched off after a ride, the air inside the device cools down and moisture condenses on the walls. A little, but if the trips are frequent but short, this water from the oil will not have time to evaporate.
To check this, simply unscrew the oil filler cap. In winter, a yellowish layer forms on the lower surface, resembling sour cream in consistency. It is an emulsion (mechanical mixture) of water with motor oil. The valve cover is covered with the same deposits.
Water is also collected in the pan. This causes the oil level to rise.
A large puddle at the bottom of the pan is especially dangerous (after all, water is heavier than oil). When it freezes in frost, the oil supply to the oil inlet stops completely. The consequences are tragic: lack of oil and increased wear of parts, leading to engine overhaul.
Emulsion on the oil filler cap.
How to prevent?
The best prevention is intensive use of the car and long journeys. For example, in taxis that drive 100,000 km per year, there is practically no water or fuel in the oil.
A recipe for personal vehicle owners: after 4-5 short trips, you should definitely make a long one. In addition, after a full warm-up, it is desirable to run the engine at high speeds.
If the road conditions do not allow to develop a high speed (more than 100 km / h), it is necessary to switch to lower gears so that the engine speed does not fall below 4000 per minute, and this mode for at least 15-20 minutes persist . During such a ride, the fuel and moisture evaporate from the oil.
Another useful thing would be the insulation of the engine compartment. An apron can be installed on the radiator grille, and the engine can be covered from above with an automatic blanket.
The auto blanket helps reduce the amount of emulsion on the inside of the valve cover as it traps heat in the upper part of the engine.
Be careful!
The oil level can rise in winter for other reasons. For example, the ingress of excess fuel will occur due to a leaking injector. Either through leaking gaskets or cracks in parts, antifreeze will seep into the oil.
If black smoke is coming out of the exhaust system or if the engine has recently overheated, it’s worth popping in for a diagnosis, without comforting yourself with the fact that the oil level is just rising due to condensate.
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