What Is Wrong With This Truck?

I was at a redlight on my way to work this morning when I saw this truck: obviously something is wrong with it!

I've seen smoke coming from exhaust stacks on these rigs in the past, but the smoke has always been black.  This smoke was white!

Is it a damaged turbo, allowing oil into the exhaust system?  Or is it water that causes the exhaust smoke to be white?

I can't imagine that the driver didn't notice something was wrong with his/her truck!