Tranny & Diffy fluid
 

How often should the transmission and rear differential fluids be changed? I've heard around every 30,000 miles. My Firehawk has 33,000 on it right now, and I'm thinking of getting it done in the spring.

That is a reasonable time frame. In a car like yours that doesn't see a ton of usage, I would be more concerned with the time frame. It may be better to make your increments more like every 3 years. Time does just as much to allow condensation and breakdown of the fluid as mileage will.

Thanks for the rule of thumb, Tim. That sounds like a good idea. The car is 7 years old. I've had it for 5 years now...so it's highly unlikely the previous owner changed these fluids in two years of use.