What oil should be used to top up oil in a bus engine?
Show the correct answer
Correct answer
B. Oil of the same class as the oil in the engine.
Explanation
In the photo you can see a yellow engine oil filler cap with an oil can symbol and the word "OIL". When topping up the oil in a bus engine, you add oil of the same class as the oil already in the engine - answer B.
The Road Traffic Act requires a vehicle to be maintained so that using it does not endanger safety. Oils of different classes and viscosities have different sets of additives - once mixed, the mixture has the properties of the worse of them and may not meet the engine manufacturer's requirements. Oil with a much higher viscosity (answer A) reaches the engine parts more slowly after a cold start, and it is exactly then that the engine wears the most. "Any" oil (answer C) may not meet the manufacturer's requirements. That is why you carry a bottle of the same oil that is in the engine, and you check its level with the dipstick with the engine switched off.
Legal basis: Art. 66 para. 1 point 1 of the Road Traffic Act (Prawo o ruchu drogowym)