I beleive that these so called requirements are bogus! I have used Prestone in my old 1977 450SL and (I dont necessarily reccomend same) I havent changed or added to Prestone in 5 years except for nuetralizer (also prestone). I beleive that m/b and some others are trying to "push" their more expensive (not better) coolant for additiona profit. Just my 2 cents worth. Abe G