"White Vinegar The slowest of the slow, the best we can say is that its inexpensive, easy to use, and aluminum-safe. Unfortunately, there are downsides. It was the most aggressive towards steel
on a mil/cleaning time basis, the scale removal
was glacially slow, accomplishing little even with an overnight soaking, and a number of cruisers reported giving up on vinegar as a preventative method after becoming unconvinced it didn't do much."