Leathermang can give you a much more accurate idea of what Trans-X does, but basically it is a varnish-type product that cleans out passagways in the tranny. Fluid is forced through said passagways which makes all the magic stuff happen.
That is the crayon version, others will give it to you in pen...
JL

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John