There's a few things wrong there.

The S80 has a quick-release connector, which required no tools. Just squeeze the tabs, push in, and pull out. Attach a 1" ID clear plastic hose to the now-open upper connection on the radiator, and run into a bucket. Idle until two quarts of fluid are pumped out. Add two quarts. Drain two quarts, Add two quarts, Repeat until fluid runs clear (took me 16 quarts). At two points during the pump-out phase, shift through the gears, waiting about 3 seconds after shifting into each one, to help the old fluid to be removed. Remove clear hose, reattach radiator hose, and idle for a few minutes. Check to make sure the level is above the minimum mark. Go drive your car gently until the engine has heated up fully and keep driving for ten minutes. Shut off the engine, and check the oil level again. Make sure it is somewhat (but not much, I filled mine to the 'ridge' on the dipstick above the "HOT" mark) above the 'HOT' mark on the dipstick.

Enjoy your new-found shifting smoothness. Check the oil in a few days, and again a week later. Add oil if needed. After a month, my oil is still bright red. I used Mobil 1 Synthetic ATF.

It's really easy once you understand the process. There is lots of confused help here - the S80 is actually quite a bit different than the 850.

Email me if you need more help.