FIrst off, I wont be leaving oil in the cooker all the time, nor did I say I would. Oil gets strained and cooker gets cleaned per the instructions from the manufacture and oil is stored in oil safe containers when its going to be a while without using it. I have only had my cajun cooker since July but there is nothing about it so far that I have found that I dont like. As far as using oil for a long length of time, I personally cant testify to that, but I will only use it if its safe and clean. Ive used the same oil since July and its in great shape. I do know this, I've had my cooker for 3 months and I really have enjoyed it tremendously so far.