Dave Plowman wrote in news: snipped-for-privacy@argonet.co.uk:
Not sure if you are talking about flushing or the original nut problem. However, (from memory alone) Consumers' Assoc. did a test several years ago on rusted up nuts in which cola drink did pretty well - better than the worst proper products but not as good as the best. For that sort of job, and assuming a one off or emergency situation, a can of cheap cola is pretty much unbeatable on price.
Rod