why are my water jackets stained orange! ive done countless head swap on many ls1's and always swap coolant to original green i hate dexcool, but anyway I take my water pump off antifreeze is perfect like always green as can be but now my water jackets are orange and this stain is flourescent and does not come off? in all my years working on cars i have never seen anything like this. it is not dexcool color or rust color its like a bright orange lol idk i just find this really weird!

 

get us some pics, sounds interesting.