Mud and debris under the oil filler cap
Light-colored deposits (emulsion) under the oil filler cap indicate insufficient moisture in the engine oil. They often occur when driving continuously with a cold engine, especially during the winter months. The condensate accumulates in the engine over time, and the oil turns into a light beige emulsion. When the block seal burns out, the coolant can get into the engine oil, which ultimately leads to the formation of an emulsion.
Dark brown tar deposits indicate heavy contamination of the oil system.
Before changing the oil and when flushing the oil system, add VitaFlush – oil system cleaner (universal) to the engine oil (mileage 400–1,000 km).
If you have the problems described above in winter, but these disappear after the engine has warmed up, this is quite normal.