Doug,

I really have not ever had overheating problems on any old Volvo with the OE radiator. Even the electric-only fan on my 2175cc motor only needs to turn on once every few weeks or so.

I think what happens is that the radiators eventually get plugged up, or the fins break off, etc., and many get recored with standard-grade cores. The OE cores are industrial grade, much denser tube and fin spacing. If you do need to overhaul yours, be sure to specify that sort of core -- two rows of that are more cooling than three rows of the standard core (ask me how I know).

Also, there has been a rash of bad thermostats going around lately. I check new ones by heating them in a spaghetti cooker/steamer thing (for easy removal) while monitoring water temp with a thermometer. Just something else to be aware of.