We study entanglement dynamics in a dispersive optomechanical Dishwasher Timer Knob system consisting of two optical modes and a mechanical oscillator inside an optical cavity.The two optical modes interact with the mechanical oscillator, but not directly with each other.The appearance of optical entanglement witnesses nonclassicality of the oscillator.We study the dependence of Timer Module the entanglement dynamics on the optomechanical coupling, the mean photon number in the cavity, and the oscillator temperature.An experimental realization with ultracold atomic ensembles is proposed.