Viscosity is the resistance a fluid experiences as it moves. Motor oil viscosity ratings are ratings developed by the American Petroleum Institute to show the resistance of motor oil at two different temperatures: high and low temperatures. Our team at Upstate Auto in Saranac Lake, NY will shed more light on these ratings.
In previous years, vehicles used one viscosity grade oil in winter and a different viscosity grade oil in summer. However, this changed with advances in technology. Vehicles can now use the same grade of oil all year thanks to additives like viscosity index improvers. Motor oil viscosity ratings have two parts: the viscosity of the oil at low temperatures and the viscosity of the oil at high temperatures.
For instance, if a viscosity rating reads 5W-30, 5W describes the viscosity of the oil at low temperatures, while 30 describes the viscosity of the oil at high temperatures. The lower the ratings, the lower the viscosity. Lower viscosity means the oil will move quickly around the engine. You can find the recommendations on the best oil to use for your vehicle in its manual.