oil mass

例句：

1. 1.The oil mass in the tank is 20%.
   油箱中的油量为20%。
2. 2. The oil mass of the engine is high.
   发动机的油量大。
3. 3. The oil mass needs to be checked regularly to ensure proper lubrication.
   需要定期检查油量，以确保适当的润滑。