In November,2001 I purchased a used salvaged 1997 Volvo 850 and I apparently need to add some coolant as the warning light has flashed and an eyeball inspection of the reservoir tank confirms the level is a little low. The manual urges 50/50 coolant/water addition using only Volvo coolant, which I hear is rather expensive. I am aware that when adding coolant, it is preferable to use the same coolant that is already in the system. The problem is since I purchased the car used, I have no idea what type of coolant is already there, whether it be Volvo coolant or otherwise. I have had no operational or overheating problems, so perhaps this indicates there is Volvo coolant already in the system, but I am not sure. Given all of these variables,should I add only Volvo coolant? Also, should I use distilled water, which I have read is highly recommended? Thanks for your help!