A pan drop, changing filter and seals, then refilling to proper level with new fluid, in my own personal opinion should not do any harm.

You will not get all the old fluid out, a substantial amount of fluid will remain in the trans to be diluted with new fluid.

Wpoll, good catch on the trans thermostat, I'd completely forgotten about that. I've never heard of it causing problems but it certainly is very possible because of what it does!

I still recommend cleaning all the transmission electrical connections as suggested by other members in your original thread. I still think its an electrical glitch but the high trans temp is something that should be checked too.

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04 X5 3.0i auto
03 X5 4.6is