The general purpose rubber covers swell considerably in most oils. The reason for this is that the rubber polymers in these grades consist of pure hydrocarbons, as do most oils, and the oil is easily absorbed by the rubber. The rate of absorption increases with the temperature.
ARB's specially designed Oil Resistant Belts are not effected by paraffin oil, naphthene-based oils, petrol animal or vegetable fats etc. and are suitable for transporting goods which contain oil.