A thermal management system for a gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a heat exchanger and a valve that controls an amount of a first fluid that is communicated through the heat exchanger. A first sensor senses a first characteristic of a second fluid that is communicated through the heat exchanger to exchange heat with the first fluid and a second sensor senses a second characteristic of the second fluid. A positioning of the valve is based on at least one of the first characteristic and the second characteristic.