Coolant Leak 93 Gs 300

[kennethsk]

93 gs 300 stock 225, 000 km

help I'm losing fluid but I can't find any on the drive way or dripping or on the hoses. Also doesn't appear to be any tell tale signs like smoke coming out of the exhaust. The coolant looks a bit murky like there is oil in it. I don't see signs of coolant in the oil. What's the problem? Any hints and directions for repair are welcome. Do the additives for head gasket damage work? If they do what brand works best?