A '93 with 40k? Wow, almost new! Anyway, on the side of your coolant expansion tank there should be two marks, Hot and Cold. The coolant should not be below the Cold mark when the engine is cold or above the Hot mark when the engine is at operating temperature.

As far as type of coolant, the Volvo manual indicates that only Volvo coolant be used. I'd guess any name brand that states it's designed for all aluminum engines would be fine. A 50/50 mix of distilled water and coolant is what you'd add. At your local auto parts store or Wal Mart you can get an antifreeze tester. Looks like a big, oddly shaped syringe with a temperature scale on it. Suck enough coolant to fill the syringe and the dial inside will give you an idea how well protected you are. If you've never had your coolant changed it would be a good idea.

Good luck,
Erwin in Memphis
'95 855t
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Regards, Erwin in Memphis, '95 855t