Translation guide
A liquid used to transmit power in hydraulic machinery. In Japanese, the most common term is 作動油, but other compounds exist depending on context.
The standard term for hydraulic fluid used in industrial and mechanical contexts.
The most common and general term for hydraulic fluid. Used in machinery, construction equipment, and industrial applications.
This machine needs hydraulic fluid.
Literally 'oil-pressure working oil'. A more technical term, often used in engineering specifications.
It's time to change the hydraulic fluid.
A common term in automotive and light machinery contexts, using the loanword オイル.
The hydraulic fluid is leaking.
Specifically for hydraulic brake systems in vehicles.
Specialized term used in aviation.
Specifically 'aircraft hydraulic fluid'. Used in technical aviation contexts.
Aircraft hydraulic fluid must withstand high temperatures.
作動油 specifically refers to hydraulic fluid. Do not use it for engine oil (エンジンオイル) or transmission fluid (トランスミッションフルード).