I only use a soft sponge and cold water to wash the element. Everything wipes off easily. No detergent or cleaner needed. About 5 mins of work.
About once a year I put a scoop of oxiclean in and bring to 180-190F for 30 mins to get looking brand new and sparkly (for no other reason that I like things to look new and sparkly).
Here's the first batch of beer after after I did that sort of cleaning:
The element at this point had seen about 60 10-gallon batches.
The only exception was the one time I used liquid hop extract (like a thick syrup). That stuff left a sticky tar-like substance all over the inside of the kettle and I spent a good 60-80 mins and 2/3 of a bottle of oxiclean spray getting everything clean. What a pain, but the Pliny the Younger clone was worth it.