I am planning to flush the coolant in a couple of months. It'll have been 3 years by then since the last flush.

I read this article on Pelican Parts on how to flush the system:
http://www.pelicanparts.com/techarti...ing_System.htm

Do any people here have any additional tips? Ways to clean out the system maybe to ensure longevity?

 

My tip is keep that water wetter on the shelf. I have no idea why people think they need to be adding silicates to their coolant but just don't. Bmw blue is all you need

 

I paid an independent MINI specialist shop to do a cooling system flush on my R55 around 55,000 miles (just a drain and fill) and within a week the thermostat housing started leaking. It had a hairline crack. I guess it was just a coincidence but I ended having to replace the housing and re-do the flush.

I would also stick to the MINI brand coolant 50/50 mix with distilled water.

 

The BMW coolant is a HOAT coolant which is good for five years or 150K miles. So you're probably just wasting time and money by changing it now: this isn't like the old conventional coolants that only lasted two years.

If you've always been using the proper coolant and distilled water and you haven't had any failures like a head gasket dumping oil into the coolant there's no need to clean anything out. Just drain the old stuff and refill/bleed with new. Easy peasy.