I would try Spray 9. On dry surface then powerwash on low pressure. you are going to think this next one strange. the guys have been using it to clean grease on OTR trucks, Monster Energy Drink. Yep, It cleans grease like Coke removes rust...
Our local scrap recycler employees called them "Chicklets". they would throw them in the metal shredder and BOOM. cleaned the teeth. Good fun till the neighbors started to complain....