It’s “anyone’s guess.” Discovery Channel:

And neither will any oil slicks that are sucked into the Loop, he said, unless there is something causing the water to mix, like a hurricane. A powerful hurricane can cause the ocean waters to mix down to 150 meters.
As for what an oil slick will do in a hurricane, it will surely cease to exist as a discreet layer on top of the water, said Trenberth. That’s because during the worst of a hurricane the ocean surface itself ceases to exist and becomes a continuum with the sky.
Rather than sticking to the water’s surface, oil would be mixed into lower ocean layers, explained Trenberth. What happens after that is anyone’s guess.