Gentlemen -- An excellent dissertation on brake system maintenance. Suggestion -- how about doing a similar one on Benz engine cooling system maintenance, to include: periodicity, what to use as the flushing agent, antifreeze choices, any additional additives, etc. etc. I understand that M-B sells an excellent citric acid flushing fluid, however believe it is also quite expensive (something like $60 per bottle). So what would be the recommendation of when and how often should one use this flush ?? Thanks.