My transmission gets more difficult to downshift as the day goes on at a track day. It does not grind, it locks me out.

see video: shift issues at 00:40,01:10,02:05

[media]http://www.youtube.com/watch?v=jDGZaO9vMpc&feature=plcp&context=C4b13d4bV DvjVQa1PpcFOQTbcD-ORPS_xEPPDOYVBT-m9u1A6rke0%3D[/media]

Has anyone had success with a different transmission fluid? There is GM MF formula, and also Pennzoil Synchromesh MTF. (Are they the same?)

My S is a high mileage car and I currently use Honda MTF. It shifts OK in normal street driving (but not as good as when new).

Thanks in advance

Jim