What does 0w40 mean for engine oil?

[DiMary]

0w40 refers to the grade of the engine oil. The number before the 'w' indicates the viscosity of the oil at low temperatures. A smaller number means better fluidity and cold resistance. The number after the 'w' represents the viscosity index of the oil at high temperatures, with a higher number indicating greater viscosity. Engine oil, also known as motor lubricant, serves to lubricate and reduce friction, assist in cooling, seal against leaks, prevent rust and corrosion, dampen shocks, and resist wear. The steps for changing engine oil are: 1. Lift the car, remove the undercover, and place a container of about 10 liters under the drain plug. 2. Unscrew the drain plug and use an air gun to blow into the oil filler for two minutes. 3. After draining, tighten the drain plug and check for leaks with a tissue. 4. Reinstall the undercover, lower the car, and use a funnel to add new oil into the filler port.