A thermal management system for a gas turbine powerplant with an engine oil line and an engine fuel line incorporates a heat transfer control module that includes a reversible heat pump with a heat pump compressor for circulating working fluid in forward and reverse directions through a working fluid line of the heat pump. The heat control module also includes a first heat exchanger having a heat exchange path for the working fluid between the compressor and a heat pump expansion valve and another heat exchange path for the engine oil. A second heat exchanger has a heat exchange path for the working fluid between the compressor and the expansion valve and another heat exchange path for the engine fuel. The heat pump can be operated in forward or reverse directions depending on whether heat is to be transferred from the engine oil or the fuel to the heat pump working fluid. In another embodiment an engine oil reservoir located between the first heat exchanger and the engine collects the oil before it is introduced to the engine and thus acts as a heat capacitor for the system.