ANTI-FREEZE
ETHYL GLYCOL......
Very familiar with this stuff being in the automotive biz.
I have used it to clean my headers. Especially when they where gunked with caster oil burnoff. I heated the stuff over a burner on my outside grill and it did clean it off perfectly.
TWO WARNINGS......
1. DO NOT inhale these vapor...very bad for your lungs and internal thangs.
2. This stuff becomes flammable after the water boils off.
BTDT
However... my header was the shiniest its ever been.