Q: Mercedes-Benz GLC 9-speed manual transmission, 2.0L displacement, after the maintenance, the power is significantly reduced, and it automatically drops after shifting to 7th gear. This minor maintenance replaced the engine oil, oil filter and air filter. Is the quality of the replaced engine oil not good?
A: During routine maintenance, changing the engine oil generally will not cause the transmission to fail to shift to high gear. You can try to remove the air filter. I have encountered many cases where the high gear could not be shifted after replacing the air filter. The main reason is that the resistance of the air filter filter paper is too large. In this case, the driver will feel that the engine power has dropped significantly and the power is insufficient.