There's no single definitive answer. However, here's a breakdown of common viewpoints:
* GM's (often outdated) guidance: GM used to often recommend "lifetime" fluid, meaning no scheduled changes. This is largely considered outdated and inaccurate. "Lifetime" usually translates to the lifetime of the transmission, which is far shorter if the fluid isn't changed.
* Modern best practice (for automatic transmissions): Most mechanics now recommend changing the transmission fluid and filter every 50,000 to 100,000 miles, or even sooner if you frequently tow heavy loads or drive in harsh conditions (stop-and-go traffic, extreme heat). A partial fluid exchange might be done more frequently, every 30,000-40,000 miles.
* Consider your driving style: If you primarily drive on highways at steady speeds, you might stretch the interval a bit longer. If you mostly drive in city traffic, shortening the interval is recommended.
In short: Ignoring the possibly outdated "lifetime" fluid recommendation from GM, it's best to get your 2007 Chevy Impala's transmission fluid and filter changed every 50,000 to 100,000 miles, or sooner if you notice any slipping or rough shifting. Consult your owner's manual and a trusted mechanic for the most accurate recommendation based on your specific driving conditions. A partial exchange is a less expensive and less disruptive alternative to a complete flush.
