I admire your desire to change the fluids often, but in the case of the new "lifetime fill" transmission, I think you're going a little overboard to change it at 40,000 miles.

As far as flushing goes, you should be VERY careful in doing this to an automatic transmission. It is somewhat common for an old transmission after flushing to be incapable of moving the car. The clutch material in an old transmission can be washed away with some of these procedures requiring an entire overhaul.

I personally avoid driving cars with automatic transmissions, but I do have experience with them. The main thing to understand about them is that HEAT KILLS. The normal temp for ATF is 170 to 180 degrees F. For every ten degrees over that temp that the ATF runs, the life of the fluid is cut in half. That's quite a telling piece of information. The best thing to do is to drain and fill the trans often and if it has a replacable filter, change that often too.

I personally would NEVER do one of the flush jobs that are promoted by some shops. The purpose for most of those services is to make money for the shop. Most especially NEVER flush a transmission that has burned fluid, that is the transmission that will lose the clutch facings in the flushing process.

Good luck,