Antifreeze Prestone or OEM Honda

I’ve never ever seen OEM Honda coolant even remotely dirty, sludged or have insufficient protection even after 100k miles.

I run the prestone green coolant in my e36 since 2006 and my 540i/6 since 2008. They're both fine. The old engine still looked & ran great. The radiator in my 540i was still from 1998 until very recently when I did a cooling system refresh - entirely preventive.

Prestone teal colored euro coolant has never failed me.

I use the Prestone 50/50 Prediluted coolant which states “guaranteed for all vehicles American/Asian/European” on the label. It is yellow/green. Zero issues because it matches the specs in the manual.

I use Prestone teal European car formula. No problems yet

OE BMW coolant should be your first choice, and if it can’t be, second would be another reputable coolant maker that offers a European vehicle variant. For example, Prestone makes a blue in color variant formulated for use in euro cars. I’ve used both, never had an issue with either.

Replace the orange stuff with new Prestone orange stuff.

For coolant - cheap Prestone (concentrate) got my old Speed3 to 60 000km no problem. I used 25% glycol and 75% distilled water and a couple caps of redline water wetter. No more overheating, even idling in +35°C.

I use the orange dexcool stuff found at most auto parts stores. I think it's prestone, but I don't remember

Prestone destroyed my passats Cooling system, everything just deteriorated, the hoses in my car started to break up. I don't recommend prestone