it is my understanding that if you have an older not-rebuilt transmission and use dextron that your abrasive material will disolve/delaminate from the backing, it is also my understanding that of you have rebuilt materials that were done in the past 15 or so years that you can pretty much count on compatibility with dextron. on another note, I knew a guy that had a trans shop that would only use the type F even in the chevy trans because he said the dextron 'slipped' more during shifts which means more wear per shift bob