I'm not disagreeing, I am just asking a question. Vinegar certainly is an acid. Acetic acid diluted to 5% to be exact. But I wonder if it would really destroy an aluminum radiator if it was used for a flush. When I flush a radiator, I run it with the flushing stuff (Blue Devil Radiator flush is good, and the bottle says safe for Aluminum Radiators) in it for about 10 minutes and then drain the cooling system, flush with water and then fill up with 50/50 anti-freeze and water mixture. I don't see how some vinegar can destroy the radiator if it is only in the cooling system for a few minutes and then flushed with water.