My grandpa who has lived on a ranch all his life uses brake fluid almost more than any other fluid around this ranch. He uses it to free rusted parts, such as the tracks on his old John Deere track loader. I can tell you, it really does work for this. Regarding tranny fluid... I had some problems with my transmission modulator and was burning tranny fluid in my Firebird... lots of white smoke for sure but my friend who is a lifelong mechanic and knows his stuff said it wouldn't hurt anything... and that it would clean the inside of the engine pretty well, too.