Motor oil is made from crude oil and is used to lubricate, clean, and cool engines. Types of motor oil include conventional, synthetic, diesel, bio-based, hybrid (blends of conventional and synthetic), and recycled oils. Motor oil varies in weight and viscosity, as well as additives that some manufacturers add to the oil during the refining process. A numerical code system created by the Society of Automotive Engineers (SAE) grades motor oils according to viscosity--the higher the number between 0 and 60, the more viscous (thicker) the oil is. Most consumer motor oils are graded by two numbers, with the first number indicating cold weather (Winter or "W") performance.

SAE 10W-40

This oil has a weight of SAE 10W-40, meaning it has an SAE viscosity rating of 10 in cold temperatures and a rating of 40 at normal operating temperature. Always check your vehicle's owner's manual to verify that this is the correct weight of motor oil for your vehicle.

Semi-Synthetic Oil

This oil is a semi-synthetic oil, meaning only some crude oil is used in making it. Semi-synthetic oil can be used in vehicle engines instead of motor oils refined from crude oil, and often provides superior mechanical performance over traditional motor oil, including increased gas mileage and reduced engine wear at extreme temperatures. Its complex method of production means it can often cost more than conventional motor oil.

Please note that you should not mix quarts of synthetic and conventional motor oils in your vehicle, and if you use semi-synthetic or full synthetic oil in your vehicle, you should not change the oil with conventional motor oil.