If you are referring to removing the varnish that builds up on the outside, I don't know about oven cleaner but there was a review in Model Airplane News about a product called Dawn Power Disolver. A club member went to Kroger and bought a bottle and tried it on a 20+ year old engine. He says he sprayed it on, waited a few minutes, then scrubbed the engine using an old toothbrush and the varnish came right off.