I was getting on 270 @ 161 (Dublin) in my Mustang a few years ago, It had just started to rain, going about 30mph I down shifted from 4th to 3rd and it was like I hit ice. I turned into the spin (I was about 70% from going around). I ended up all the way over into the slow lane before I gained control. Luckily traffic was light and everyone hit the brakes. That shit will sneak up on you quick!
EDIT - auburn pro diff and 373's don't help