When do you close the drain when adding new oil?

The appropriate time to close the drain while adding new oil is when the oil pouring out becomes clear. This indicates that the system has been properly flushed of old, contaminated oil and that the new oil is being introduced without mixing with residue or impurities. Ensuring that the drainage is clear before sealing is vital for maintaining the integrity and performance of the lubrication system.

This practice helps in removing any contaminants or degraded oil that may have been present, ensuring that only clean oil remains in the system to protect the components efficiently. By closing the drain at this point, you can be confident that you've minimized potential contamination of the new oil, leading to better operational efficiency and longevity of the machinery.

The other scenarios do not align with the best practice for oil replacement. For example, waiting until the oil reaches the maximum level does not ensure the removal of impurities. Observing oil temperature stabilization may relate to performance conditions rather than oil quality at the point of entry. Replacing the filter is a critical maintenance step, but it does not dictate when the drain should be closed during the oil replacement process.