紅油

Wikipedia has an article on:

• 紅油

紅油

1. (dialectal Mandarin) chili oil

   紅油抄手／红油抄手  ―  hóngyóu chāoshǒu  ―  chili oil dumplings

2. (Hong Kong) undutied diesel for industrial or shipping purposes (which is marked with red dye)
   • 1999 July 14, Hong Kong Government Press Release, 使用紅油作汽車燃油屬違法行為 (Using "Red Oil" as Motor Vehicle Fuel is Illegal)‎:

     海關發言人指出，使用紅油作汽車燃油屬違法行為。 [MSC, trad.]
     海关发言人指出，使用红油作汽车燃油属违法行为。 [MSC, simp.]

     Hǎiguān fāyánrén zhǐchū, shǐyòng hóngyóu zuò qìchē rányóu shǔ wéifǎ xíngwèi.

     The Customs spokesperson states that using "red oil" as motor vehicle fuel is illegal.

   • 2019 July 2, Ta Kung Pao, 深海關查獲1.7億元走私「紅油」 (Shenzhen Customs Seized "Red Oil" Worth Over ¥170M)‎:

     海關相關人士介紹，由於內地禁止使用「紅油」，因此走私分子需要把走私「紅油」的紅色染料過濾掉，還原成普通顏色的柴油，然後再出售。 [MSC, trad.]
     海关相关人士介绍，由于内地禁止使用「红油」，因此走私分子需要把走私「红油」的红色染料过滤掉，还原成普通颜色的柴油，然后再出售。 [MSC, simp.]

     Hǎiguān xiàngguān rénshì jièshào, yóuyú nèidì jìnzhǐ shǐyòng “hóngyóu”, yīncǐ zǒusī fēnzǐ xūyào bǎ zǒusī “hóngyóu” de hóngsè rǎnliào guòlǜ diào, háiyuán chéng pǔtōng yánsè de cháiyóu, ránhòu zài chūshòu.

     As "red oil" is prohibited in Mainland China, customs officers says smugglers needs to remove red marker in diesel to return into its original colour before selling.

• 辣油 (làyóu)
• 辣椒油 (làjiāoyóu)

紅油

1. (Cantonese) red paint, especially as a tool of vandalism

   淋紅油／淋红油 [Cantonese]  ―  lam⁴ hung⁴ jau^4-2   ―  to daub with red paint (as a way to harass loan shark victims)