synthetic oil

例句：

1. 1. The synthetic oil in the engine is causing a lot of problems.
   发动机里的合成油导致了很多问题。
2. 2.The chemical engineers used to use this kind of synthetic oil for their experiments.
   化学工程师过去常用这种合成油进行他们的实验。
3. 3.The car's engine has been replaced with a new synthetic oil.
   汽车的引擎已经被换成了新的合成油。