What causes the abnormal noise when starting a Mercedes-Benz C260L?

[StEmilio]

Mercedes-Benz C260L starting with abnormal noise may be caused by parts noise or prolonged use of transmission fluid. Parts noise: The car's gear shifting structure consists of the gear lever, cables, gear selection and shifting mechanisms, shift forks, and synchronizers. The noise from these parts is relatively small. Prolonged use of transmission fluid: Prolonged use of transmission fluid can lead to sludge formation, increasing the wear of friction plates and other components. Wear in these parts can cause malfunctions resulting in noise. If the sound during gear shifting is relatively small and comes from near the gear lever, it is normal noise from the gear shifting mechanism. If the gear shifting produces a clicking sound, it is caused by a fault in the transmission gear impact.