There are many different types of motor oil on the market and for the uninitiated it can be a bit confusing. For most people the choice between mineral, semi-synthetic or synthetic would be the biggest concern. The bottles or canisters also have numbers and letters on them and for many, this can be the cause of most confusion. Most cars will run quite happily on 10W/40 multi grade but remember to choose the correct one for the type of fuel the car runs on. The numbers just refer to the ambient temperature the oil will work at and the viscosity of the oil.