[nexium]

Thanks for bringing these points out. In reference to the flush chemicals- if it did dissolve the gunk in the filter, wouldn't it also start to work on the rest of the parts, where the gunk came from?
If the fluid exchange is in the normal direction (as opposed to backflushing), the particulate would be caught in the filter wouldn't it? I think this means the filter should be changed after the flush.
I've had very good luck with doing a filter and partial fluid change at 40K intervals. My only failure was a Ford A4LD, with a front seal leak.
From the stories I hear, it's probably best to adhere to the manufacturers recommendations as long as you're under warranty.