This is probably a dumb question but can a thicker oil then required cause your tranny to shift abnormally,or does one have nothing to do with another?
According to this report Toyota says it tests it oils in it's racing teams and are PAO based.
Just doing some research into what might also be in the tgmo 0w20
http://www.trdparts.jp/english/parts_oil.htm
TGMO 0w20 for tubrocharged cars too! apparently says so right on the can its an amazing oil,heres the link http://www.ft86club.com/forums/showthread.php?t=67527