G'day Guys,
My A10 doesn't blue the pipes, it runs more on the rich side, but my bonnie used to. I had some success with keeping it at bay
by using Prepsol (wax & grease remover), sounds strange, but give it a try! Soak a rag in prepsol, give the area a rub, then leave
a good coating on it to evaporate off. It doesn't completely remove it, but takes it back to the original blueing that took place.
regards, Cus