Cooling system loses water but no visible leaks. Have to add one quart of water to radiator every 30 minutes of driving. Reservoir still full but need to add water directly to radiator. Oil not discolored. Can’t figure out where water is leaking to. There is a very, very minor seep at one side but water evaporates before dripping to ground. Can water leak directly to exhaust? What other explanation is there?
Blown head gasket is the other explanation. There is a test kit for this.