Although we like to blame GMO's for everything, that is not the problem here. As oil breaks down it will cause foaming.
Here is a good link. The part about foaming is addressed under oil freshness and you will see that the type of food and the type of coating being fried affects the breakdown at different rates but ALL oils will break down after repeated use. Filtering used oil is a good idea to remove food and coating particles from the oil.
http://www.seriouseats.com/2013/09/a...e-fry-oil.html