HoustonYank

On my '07 550SL, w/60K miles, just started hearing a squeaking sound coming from my left front end. When I push down on the left front it squeaks. When driving I hearing squeaking sound when turning, even while not moving, as well as when driving. Interesting, I added some fluid to the ABC tank and it stopped for a bit, then started up again, but not low in reservoir. No problem with right front. The fluid seems a little brown and was wondering whether I need to flush the system. I'm also considering going with coilovers if it turns out to be struts or ABC issues. Any advice greatly appreciated.
Thanks
Dennis