I was reading the archives and seemed to have learned something new. I was always under the impression that a tranny flush via the cooler lines will clean out yer WHOLE tranny of any old atf as opposed to just draining the pan, which will only get out a few qts. so I was surprised to read that to get a 100% or close to 100% flushing of atf, one has to drain the pan (clean and add new filter if necc.) and then do a flush via the cooler lines. I thought a flush was sufficient enough. is this true? or are some people just super duper complete about having clean fluids?

also, today I looked under my car and found the OD solenoid (thanks faq). it's a lot bigger than the picture. I noticed the rubber cap is broken and a bit brittle. does this cap cover any openings at all? and is changing one a diy job for the diy neophyte? I want to do some preventive maintainance.

You first drain and refill the pan, then flush the remaining fluid through the lines. This will extract virtually all the fluid. The pump sucks up fresh fluid from the pan to replace the old fluid being pumped to the cooler and into your bucket. All you need do is replace the fluid being pumped from the pan.