Methods and systems are provided for a dual loop coolant system used to control an engine temperature. In one example, cooling capacity is transferred from a low temperature loop to a heat exchanger, and cooling capacity stored in the heat exchanger is transferred to a high temperature loop (e.g., an engine coolant loop). The flow of coolant from the dual loop coolant system to the heat exchanger may be regulated responsive to a temperature of the coolant in each of the low temperature loop and the high temperature loop.