Read this: The ideas of the Italian Renaissance were slow to cross the Alps into northern Europe, but important artistic innovations were made also in the Low Countries. Though not – as previously believed – the inventor of oil painting, Jan van Eyck was a champion of the new medium, and used it to create works of great realism and minute detail. The two cultures influenced each other and learned from each other, but painting in the Netherlands remained more focused on textures and surfaces than the idealized compositions of Italy.

What painter wasn't an early champion of oil as a medium in painting?
What is the answer? (If it cannot be answered, return "unanswerable")
unanswerable