When do you Change transmission fluid in a 2004 Chevrolet Impala?

The recommended transmission fluid change interval for a 2004 Chevrolet Impala depends on several factors, including driving conditions and the type of transmission (automatic or manual). Chevrolet's owner's manual is the definitive source. However, generally, for automatic transmissions in a 2004 Impala, a fluid change every 100,000 miles was often recommended, though some sources suggested 60,000 miles or even sooner, depending on harsh driving conditions.

Crucially, "change" can mean different things:

* Drain and refill: This involves draining some of the old fluid and refilling with new. It's less thorough than a complete flush.

* Complete flush/exchange: This uses a machine to pump out most of the old fluid and replace it with fresh fluid. This is generally more expensive but more effective at removing contaminants.

Harsh driving conditions (frequent towing, stop-and-go traffic, extreme temperatures) would justify more frequent changes. If you are unsure, checking your owner's manual is the best course of action. Even then, it's a good idea to consult a qualified mechanic for advice tailored to your specific vehicle's use and condition.