軽 油(けいゆ)

けいゆ

noun

diesel fuel; light oil

1. diesel fuel; gas oil; light oil

A petroleum product used as fuel for diesel engines. Called 'light oil' in Japanese because it is lighter than heavy oil, though it is not the same as gasoline.

この車(くるま)は軽油(けいゆ)で走(はし)る。

This car runs on diesel.

軽油(けいゆ)の値段(ねだん)がまた上(あ)がった。

The price of diesel went up again.

ガソリンスタンドで間違(まちが)えて軽油(けいゆ)を入(い)れてしまうと、エンジンが壊(こわ)れることがある。

If you accidentally put diesel in at the gas station, it can damage the engine.

Composed of 軽(けい) (light) and 油(ゆ) (oil). Despite the name 'light oil,' 軽油(けいゆ) refers specifically to diesel fuel, not to a lighter form of gasoline. The name distinguishes it from 重油(じゅうゆ) (heavy oil/bunker fuel).

Caution for learners

At Japanese gas stations, fuel nozzles are color-coded: green for 軽油(けいゆ) (diesel), red for レギュラー (regular gasoline), and yellow for ハイオク (premium gasoline). Do not confuse 軽油(けいゆ) with 軽(けい)自動車(じどうしゃ) (kei car) — kei cars typically run on gasoline, not diesel.

Common collocations

軽油(けいゆ)車(しゃ) — diesel vehicle
軽油(けいゆ)価格(かかく) — diesel price
軽油(けいゆ)を入(い)れる — to fill up with diesel

Related words

ガソリン — gasoline
重油(じゅうゆ) — heavy oil, bunker fuel
ディーゼル — diesel (the loanword, used for engines and technology)
灯油(とうゆ) — kerosene

Related Words

Related: ガソリン (gasoline)

Related: 重油(じゅうゆ) (heavy oil, bunker fuel)

Related: 灯油(とうゆ) (kerosene)

Related: 原油(げんゆ) (crude oil)

Compare: 燃料油 (fuel oil)

general

Added 2026.3.27 8:27 · Revised 2026.9.2 13:01

19500/19777_keiyu