Probably normal. Even Amsoil will leave a yellowish tint. But if you are talking about a measureable amount of brown varnish that continues to build up over time, you may want to consider flushing and switching oils. (But you'll never completely remove the surface color on the metal - which, again does not mean anything bad....it's the clogging of oil galleries that worries me)
--
http://www.fidalgo.net/~brook4/oilslubesfilters.html

You'll see that stuff on almost ANY engine that uses normal petroleum based oils. In itself, that won't be the demise of your engine.
Now, the cleanest engine looking components I've ever seen on dismatelled engines came from engines that used Amsoil (dismantelled for reasons not related to oil either btw, like a bad head gasket, not a Volvo). I now use Amsoil in my cars.
I see that varnish in most engines but other than coloring the parts, I can't say that it's the reason why any engine might have oil related problems in later life, assuming that oil is changed as often as need be.
So, don't worry about it.

Same gunk on mine, don't think it's anything to worry about though.
--
96 850 GLT 5-Speed

Hi ya,

I have a 94 N/A 850 and i did have this type of symptom you describe on the head of the engine. Its not a porblem its the lacquer that is applied to the engine to stop the corrision. It dulls over time and crack in places.

I initially tried cleaning it with resin polish but i didn't get far. After seem a friend's 960 who had totally polish his inners i decided to have ago myself. The only problem once you do this is you have to keep it waxed otherwise the polish bit can corrude unfortunately.

Mark.
UK VOC 94 850glt 2l 20v 189k miles

I actually went out and looked. No, not on mine. Do you use synthetic oil or dino-juice?

-Punxsutawney Phil

'98 V70T5M, white, 112k mi., sport suspension, Mobil-1, iPd stabilizer bars, Volvo strut tower brace and skidplate, Valentine-1

http://www.groundhog.org

This is no help but mine's the same.