What type of coolant should you use in a 2002 BMW 530i?

There is little difference between the various brands of commercial automotive coolant on the market. Prestone may make this claim, and Zerex may make that one. The bottom line is that the Society of Automotive Engineers and the auto makers themselves have minimum requirements for auto coolant. And surprise! all the coolant manufacturers make coolant that conforms to at least the minimum standards. If in doubt, call your BMW dealer, ask for the service department, and inquire about what they recommend. It is far and away more important the the cooling system be serviced and maintained properly (and regularly!) than it is to find a "perfect" coolant.