Car engines need oil. The oil lubricates the engine: it keeps the parts moving smoothly. Roads are dirty and the air is dirty. Some of that dirt gets in the oil. Dirty oil is bad for the engine.
So, we need to change our oil. The car’s manual explains when to change oil. My manual says every 15,000 km. The gas station says every 5,000 km. I trust the manual. Which do you trust?
Also, you should never drive your car more than a year without an oil change.
君の為に 