* Type of transmission: Automatic transmissions generally require more frequent fluid changes than manual transmissions (which rarely need fluid changes unless there's a leak or other problem). Even within automatic transmissions, the type (conventional, CVT, dual-clutch) impacts fluid life and service intervals.
* Driving conditions: Frequent stop-and-go traffic, towing heavy loads, or driving in extremely hot or cold climates puts more stress on the transmission fluid and shortens its lifespan.
* Vehicle manufacturer recommendations: This is the most important factor. Consult your owner's manual; it will specify the recommended service interval for your specific vehicle's transmission. Some manufacturers recommend fluid changes every 30,000 miles, others every 60,000 miles, some even 100,000 miles or more, and some specify a "lifetime" fill which may never require a change. However, even "lifetime" fluids degrade over time and mileage.
* Fluid condition: If the fluid is dark, smells burnt, or contains debris, it needs to be changed regardless of mileage.
Instead of focusing on a specific mileage or time interval, it's crucial to follow the manufacturer's recommendations in your owner's manual. Ignoring these recommendations can lead to premature transmission wear and costly repairs. Regular inspection of the transmission fluid is also a good preventative measure. A mechanic can check the fluid's condition during a routine service.
