A method of operating a multi-engine aircraft includes operating a first engine of the aircraft to provide motive power; and operating a second engine of the aircraft in a standby mode to provide substantially no motive power, a rotor of the second engine having an idle rotational speed in the standby mode, and in the standby mode, sequentially executing cycles, a given cycle of the cycles including: opening a set of variable guide vanes upstream a compressor section of the second engine, spiking a rate of a fuel flow to a combustor of the second engine, the spiking and the opening timed to increase a rotational speed of the rotor of the second engine to an upper threshold above the idle rotational speed of the rotor, and in response to the rotational speed reaching the upper threshold, at least substantially closing the set of variable guide vanes.