What applications require Type II transformer oil?

“Type II” often refers to a classification within a national or utility specification (for example, inhibited vs uninhibited, or higher oxidation stability). It is typically required where longer oxidation life, better sludge control, or specific corrosive sulfur limits are needed, such as higher temperature service, sealed units, or long maintenance intervals. The exact meaning depends on the governing standard or purchaser specification, so it should be matched to that document.