How to Compare Automobile Oil

Using the best kind of automobile oil for your vehicle can extend the life of the engine, increase gas economy and reduce the number of repairs needed. Understanding the different types of motor oil is the first step in comparing and choosing the right kind. 

• Look at the number if front of the W, labeled on the front of the bottle of motor oil. This number indicates the weight, or viscosity. Viscosity determines the flow and thickness of the oil. Higher numbers mean higher viscosity. Numbers that are too low indicate oil that wears thin and will not stand up in the engine. Oil with high numbers may be too thick, slowing down components and not pumping fully.


• Take note of the number after the dash on the label. This indicates the viscosity index, which measure the oil’s resistance to change in viscosity during use. Higher numbers are favorable. This indicates a low rate of change in viscosity and higher stability. This keeps bearings running smoothly at all temperatures.


• Determine if the oil is mineral-based or synthetic. Mineral-based oil is the traditional motor oil that has been used for years. Synthetic oil has become more widely used in recent years. Synthetic oil leaves fewer deposits in the engine. It is also has more stable viscosity within the engine and can stand up to higher temperatures. Synthetic oil does not need to be drained and replaced as often as traditional oil.


• Consider the flash point of the oil. This can be found on the bottle or on the company’s website. The flash point is the degree of temperature at which the oil begins to five off vapors. Low flash points can cause vaporization within the engine and loss of oil.