What is a common guideline for maintaining a vehicle's transmission fluid?

Checking transmission fluid regularly, such as every 15,000 miles, is a common guideline because it helps ensure that the fluid remains clean and at the proper level to facilitate smooth operation of the transmission. Transmission fluid lubricates the components within the transmission, helping to prevent wear and tear, and it also helps manage the vehicle's hydraulic systems.

By adhering to this guideline, drivers can help prevent potential transmission issues that could arise from dirty or low fluid levels. Regular checks can help identify problems early on, allowing for timely maintenance or fluid changes before they escalate into more serious and costly issues.

This frequency is usually aligned with the maintenance schedules recommended by many vehicle manufacturers, who provide specific guidelines based on the type of transmission fluid being used and the vehicle's driving conditions.