Works fine one day, next day it gets stuck to the floor and won't let me take the car out of gear until the car dies then I pull the pedal out or keep trying to push it back in until it lets me put the car back in neutral. Sometimes the clutch works perfect and then others it feels like there's no resistance until the engagement point, then it won't release as well as it should. I'm not sure if this is a problem caused by cold weather (-15 to -40 all winter) or if I have to remove the transmission to check for a more serious problem. It's at it's worst when in 1st or reverse. Once I'm going it seems fine but like I said above, the clutch doesn't release that well, it comes back up slower than usual. When I'm stationary and the car is off or in neutral it acts normal... There's fluid in the reservoir, but it's darker than usual. I changed the fluid only a few months ago at the same time I changed the brake fluid and the brake fluid is still gold while the clutch fluid is dark brown. I will change the fluid but I know that's not the issue.

Any help would be appreciated as I want to sell the car and have a buyer but need this fixed.

 

Replace the hydraulics...master, slave and hose.
Problem fixed.

 

I guess that would be the easy way out instead of trial and error. Will s4 parts fit s5's?

EDIT: Answered my own question. Even new these parts are cheap. I could replace both cylinders and the hose/hardwires for under 100$ new.

How would someone rate the difficulty of replacing these parts on a 1-10 scale. I'm not too mechanically inclined.

 

If you look at the parts and then have to ask, the difficulty rating is hard to judge.

I would consider the job to be conceptually/mechanically very simple but access can be tough and require some gymnastics.
You can make life a little easier by doing an oil/filter change at the same time...access to the slave is more open when the filter is removed.
There is no easy way to improve access to the master mounting studs short of removing the dash, so just suck it up and deal.

 

It'll save me a ton of cash doing it myself I assume and I have use 24/7 of my dads heated work shop.

I have one last question, is the clutch slave cylinder the same as the release cylinder? My Haynes manual shows a clutch cylinder but I can't find anything like that on eBay or mazdatrix, but do see clutch slave cylinders.

 

They are commonly called "master" and "slave" cylinders.