A lot of people replace the pcv hoses at around 100K miles, so at 180K, if they've never been done, you should do it. www.fcpgroton.com sells a kit for this...total with a intake manifold gasket will run you about $130 (you'll have to call them for the kit as it's not specifically listed on their site). They are the cheapest and only ones I know of who have put all the pieces together (including the oil trap which needs changning out) as a "kit." Now, here's the kicker. Although the pcv hose(s) replacement isn't that hard, it's time consuming and requires taking the intake manifold off as well as taking the injectors loose of the fuel rail. I did mine and it took me most of a day. So, if your dealer is willing to do all of the above for $300 including parts, I'd say let him do it. Just make sure he is replacing the oil trap and cleaning out the pcv valve at the bottom of the intake hose along with changing out the hoses and cleaning the throttle body. I'd say it's a very good deal. Most dealers want twice that much.

Now for the sludge....this is also fairly common on cars that never get up to a good steady temperature. It's condensation in your engine and happens in Volvo's that are used often for short trips where the car never really thoroughly warms us. So, take her out, get her on the interstate and driver her hard occassionally for more than a few minutes to burn all of that stuff away.

Hope this helps.
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon. My cars have been running so well lately they've got me worried.