A powertrain waste heat recovery system includes a first powertrain component and a second powertrain component. The powertrain waste heat recovery system also includes a heat recovery circuit circulating a heat recovery fluid through a heat recovery heat exchanger. The heat recovery heat exchanger transfers heat from the first powertrain component to the heat recovery fluid during a powertrain propulsion mode and transfers heat from the second powertrain component to the heat recovery fluid during a powertrain retarding mode. The powertrain waste heat recovery system also includes a conversion device for converting thermal energy from the heat recovery fluid to an energy form other than thermal energy.