China is freaking out after discovering the 'open secret' that its cooking oil was ferried for years in chemical tanks that weren't cleaned

• China was hit by another major food scandal, this time involving cooking oil in chemical tanks.
• State media found that tank trucks were delivering chemicals and edible oil interchangeably without cleaning.
• The revelation ignited an explosion of backlash from the Chinese public this week and calls for investigations.

A new cooking oil scandal has erupted in China, about a decade after the country's infamous crackdown on restaurants reusing gutter oil and sewage grease.