Coolant

[meppadua]

BMW Coolant is expensive, what other brand is safe to use for m42 engines?

[Slowered318]

Technically any liquid will act as a coolant but the blue coloured "antifreeze" from BMW is formulated to preserve the components of your cooling system. Make sure you mix with distilled water, the minerals and chlorine in tap water can also cause problems.

I wouldn't skimp on the cooling system. Ask anyone who's overheated a BMW, to save a few dollars here is not worth it.