I've used the plain, yellow/green Ethylene Glycol stuff (Prestone, various house brands, etc.) in the family Volvos for a long time with no problems seen. If you change the stuff every 2-3 years it should be perfectly good. The anti-corrosion and anti-foaming, etc. additives get consumed over time - that's the main reason for changing. The gen Volvo stuff may be the champagne of antifreezes, but I'm kind of a beer guy.

By all means follow the advice below to give the system a good flush with some agent designed for the purpose. After rinsing out, pour in a 4 qt jug of pure antifreeze and fill with distilled water ($1.50/gal at Safeway). Too much mineral content and dissolved solids in most tap waters. This will get you a 40% (or so) concentration which will give freeze protection to around -15F and a fresh additive package. You'll have to up the dosage if you want to drive to Minnesota in January.

Please dispose of used EG properly - the stuff is extremely toxic to small animals and children, and they can be attracted by the sweet taste. A teaspoonful can kill a cat. In my province of BC, a law goes into effect this year requiring EG to incorporate a bittering agent to make it unpalatable to anyone or anything.
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Bob: son's 81-GL, dtr's '94-940, my 83-DL, 89-745(V8) and 98-S90. Also 77-MGB and some old motorcycles.