What are the viscosity requirements for German car engine oil?
2 Answers
German cars generally use 5W-40 viscosity lubricating oil. Engine oil viscosity grades: The W in oil grades stands for winter. A smaller number before the W indicates better low-temperature fluidity of the oil, meaning the oil has stronger cold resistance (inverse relationship). The number after W represents the kinematic viscosity standard at 100°C, divided into 20, 30, 40, 50, and 60. Types of engine oil: Based on engine types, oil can be categorized as diesel engine oil and gasoline engine oil. In terms of quality performance, oil can be classified as full synthetic oil, semi-synthetic oil, and mineral oil. It can also be categorized by viscosity grades such as 5W-20 and 20W-40. Different types of oil have varying viscosities at different temperatures, with different cold and heat resistance properties.
I've been driving German cars for over a decade, like my BMW X5, which has quite stringent engine oil viscosity requirements. The manual typically specifies 5W-30 or 0W-40. The number before the W represents winter fluidity—lower numbers like 0W allow for quicker starts in cold weather. The numbers after, such as 30 or 40, indicate high-temperature viscosity. Too high a number can make the engine sluggish, while too low may lead to oil leaks and part wear. German engines run hot and under high load, so Mercedes and Audi also recommend these grades; otherwise, fuel consumption increases and pistons can get damaged. In summer, I use 5W-40 for engine protection, switching to 0W-30 in winter for easier starts. Synthetic oil is a must, with brands like Castrol EDGE meeting VW certifications. Don’t forget to check oil levels monthly—temperature swings affect viscosity performance, and the wrong choice can cause loud noises and sluggish acceleration.
