This has been specially formulated to be used in oil-fired vaporising cookers such as Agas and Rayburns. Additives slow down the rate of deposit growth and therefore help to avoid operating problems that can occur between regular services. These can lose heat or cut out due to deposits forming on critical components. Deposits are formed as fuel oxidises when in contact with hot surfaces for a long period of time. Many factors impact the growth of deposits – including the standard of maintenance and also fuel quality.