0W40

0W-40 is a multigrade engine oil viscosity grade defined by the Society of Automotive Engineers (SAE) as having a 0 for winter cold-temperature viscosity and 40 for high-temperature viscosity. The 0W designation means the oil remains fluid at very low temperatures, aiding cold starts, while the 40 indicates the oil maintains sufficient thickness to protect engine parts at normal operating temperatures.

Most 0W-40 products are fully synthetic, engineered to offer high shear stability, strong wear protection, and good high-temperature performance. They are suitable for turbocharged and performance engines, as well as many diesel and gasoline engines. The formulation aims to provide reliable protection across a broad range of operating conditions and climates.

0W-40 oils are designed to meet various standards. They commonly carry API classifications such as API SN or SP, and ACEA classifications such as A3/B4. Many also satisfy OEM specifications from European manufacturers (for example BMW, Mercedes-Benz, Porsche, Volkswagen, Volvo). However, individual oils vary in which standards they meet, so users should verify the product’s spec sheet against their vehicle’s requirements.

Typical use includes modern passenger cars and light commercial vehicles operating in a wide range of climates. In cold climates the 0W rating provides easier cold starts; in hot climates, the 40 high-temperature viscosity gives protection against thinning. Drain intervals are determined by vehicle manufacturers and the oil type; synthetic 0W-40 oils are often marketed toward longer intervals but should be changed according to the owner’s manual or service schedule.

Always check the owner's manual to confirm the correct viscosity and specifications for your engine. Using the wrong oil can reduce protection and efficiency.