A product made from plastic and composed, at least in part, of a thermoplastic molding composition which comprises polyamide and comprises from 3 to 30% by weight of a conductivity black, where the conductivity black is defined by the following parameters: a) DBP absorption of from 100 to 300 ml/100 g; b) a specific surface area of from 30 to 180 m2/g; c) an ash content of less than 0.1% by weight and d) a grit content of not more than 25 ppm, has improved heat-ageing resistance, and also improved resistance to peroxide-containing motor fuels.