Q3 How will I buy the Valvemaster additive? Where lead replacement petrol (LRP) is available, a valve seat protection additive such as Valvemaster is premixed into higher octane unleaded petrol. Valvemaster is also available in a single treat applicator sufficient for 20 litres of petrol for dispensing on the forecourt. This is for use with unleaded petrol or as additional protection for use with LRP for heavy-duty applications. Alternatively there is a 250-ml take-home bottle, available from some outlets.