If that's what you want just change it and add some lucas. Lucas is like honey, mine's a little stiffer now but I don't really see it as better in any way. I'd change it every time you change transmission fluid, 30-50k miles depending on your city/freeway driving ratio.
I wrote this how-to, here it is in case you want to see it: http://www.grandprixforums.net/threa...00-3-8L-Engine