Only the official BMW coolant can perform its task reliably and won’t harm the engine. The BASF Glysantin G48 is regarded as one of the best variants, but don’t forget to change the coolant every 3-4 years (if your car is 6 years old or even older). It’s also important to flush out the cooling system after repair works performing. The Glacelf Plus Total, Mobil Frostschutz 600 ExxonMobil, and Aral Antifreeze Extra Aral AG are typified as decent coolants for BMW usage, so it’s better to check the manufacturer’s recommendations (read the manual) and then make a choice.