We had to drain the oil out of the engine.

我们必须把发动机里的机油全部放掉。

《牛津词典》

Out in the shaft loaded oil ring groove or by centrifugal force along the axis of the oil drain off the surface, the oil flows back to the assembly after the pool, and thus play a role in sealing.

在轴上开出沟槽或装上油环，借离心力将沿轴表面外流的油甩掉，集结后流回油池，因而起到密封的作用。

youdao

Drain the oil before demount accumulator. First let out the nitrogen with the charging device, then the parts can be demounted.

卸下蓄能器前必须卸去压力油，使用充气工具放掉皮囊中的氮气，然后才能拆下各零部件。

youdao

There are some systems that actually will take a circle and drop it just below the surface of the water and have the oil kind of flow into it, almost like a drain, recover it and pump it out.

WHITEHOUSE: Daily Press Briefing