How much water do you add to a BXT65-650 motorcraft battery?

For a BXT65-650 Motorcraft battery, you should only add distilled water to the cells if the fluid level is low and the plates are exposed. Typically, fill the cells to just above the plates but do not overfill, as the electrolyte expands when charging. It's important to check the specific guidelines provided by the manufacturer for the best practices regarding maintenance. Always ensure the battery is fully charged before checking the fluid levels.