What do those numbers mean? The oil grade represents how thick or thin the oil is (aka the oil’s viscosity) at a specific temperature. In the case of 0W-30, your oil will run thicker or thinner depending on how hot or cold it is. In the winter, the viscosity will stay low, meaning the oil will circulate more easily and help to warm your car up faster. But as the temperature increases, so will the oil viscosity.
Synthetic oils are a blend of chemicals that help clean and protect your engine as it runs, so you tend to have to change them less often.
Basically, it’s all of the savings with none of the hassles.