Formulations based on TPO, a matrix known to be particularly sensitive to these phenomena, were subjected to accelerated aging tests, in air at 85 °C for 85 days, to determine the effectiveness of antioxidants over time and under thermal stress. OIT was measured throughout the aging process. Resveratrol showed very good long-term stability, particularly at low content. BDO-3,4DHB was shown to be promising for long-term antioxidant activity.