I have never had a crock pot treatment pit or attack aluminum. I don't think there is ANY anti freeze sold these days that isn't comparable with aluminum since there is so much of it in the radiators, heads and engine blocks these days. Someone may have a 40 year old jug of old stuff that has been sitting in the back ot the top shelf in the garage! I use low heat on my stuff. It will take paint off. Older SuperTiger engines are painted, or have some kind of coating on them. I don't know if the blue OS engines are painted or powder coated, and I haven't had the need to crock pot one yet. One product I have been meaning to try on an old, crusty engine or muffler is paint remover. I have some of that Z-Best engine cleaner and that is what it smelled like to me and if I got some on my hand is burned the same way! The stuff that has airplanes on the can should be OK for aluminum.
Type at you later,
Dan McEntee