I never run a DC engine on my DCC layout!! When stopped the DC only engine sends track power to the motor and it will overheat as the motor gets some cooling from turning thus changing power to different windings. If stopped then only one set of windings gets all the power thus allowing the 2 windings to overheat. I do have a switch to control whether I run DC or DCC on the layout and my switch control is not connected to track power.