could just be hydrogenated oil... alot of the oil I use does this even in summer. With temperature change more and more becomes the thick creamy stuff.

When I heat mine to 110 or so it all goes dark and liquidy.
Of course I can't see your oil, so don't take this as fact.... I'd pull some and heat it, see what it does, or even pull a gallon og the pure creamy stuff and make a mini batch of bioD and see how it goes.