<HTML>OK, well i'm the guy from the "cleaning aluminium engineblock topic.
well this block is at least 4 years old and has been used in a normal way.
I used acestone & white spirit to degrease it, ti'll it looks like an old aluminium piece with no dirt on it. Then I used a special tool you can fit on a dril. It scrapes a little layer of, leaving new and shiny aluminium. To protect it from oxidation, I then used a special polish, et voil