The "Lifetime" Transmission Fluid
I often get asked how often am I supposed to service my transmission fluid? Best place is to consult your owner's manual as to how often. If you have one of those "lifetime" fluids or "sealed transmissions", you may want to consult your car goals and see about how long you want to keep your vehicle. Many times "lifetime" can mean whenever the manufacturer warranty on the transmission expires. If you plan on purchasing a new car every 50,000 or 100,000 miles then maybe you don't want to spend the money on maintaining it. Which is okay. I rather someone be mentally aware of their automobile expectations than spend money needlessly.
My personal opinion on the lifetime fluid is the manufacturer keeping cost of maintenance low to attract consumers to their brand and sell more cars. When you end up taking it your vehicle in for shifting problems, I'm sure the dealer will be happy to show you the new models...
Everyone drives differently so the need to change the fluid varies upon a number of factors. My grandmother in her Lexus sedan drives much differently than my sister in her Chevrolet Camaro. (Grandma is more aggressive, but that's for another post...) Do you do mostly short trips? Do you tow? Do you mostly do highway? Stop-and-go? Temperature has a large impact on fluid break down.
Many manufacturers (like Toyota) have intervals for drain and fills every 15,000 miles. So about every third oil change. Some European manufacturers which recommend the filter replacement say every 50,000 miles. The rule of thumb for the Fluid Exchanges/Flushes is every 30,000 miles. (Different types of services will be covered in a separate post.)