Each vehicle requires a specific type of motor oil, it is important you choose the correct specification of oil for your vehicle, if you're unaware of this use our Oil Advisor. Choose your engine oil by Grade / Viscosity, The first number '10W' is the viscosity of the oil at cold temperature and the second number is the viscosity at 100 °C (212 °F). The lower the "W" number the better the oil's cold temperature/cold start performance, The 40 in a 10w-40 simply means that the oil must fall within certain viscosity limits at 100°C. The lower the number, the thinner the oil, for example a 5W-30 oil is thinner than a 5W-40 oil at 100°C etc. Please use your handbook or our oil advisor, for information on what specific oil your vehicle requires.