I'm at 205K as well--2004, 545i

 

What repairs have you had to make along the way and what has your service regimen been?

Thnx!

 

I'd really like to change mine every two years if I could find out how to drain it I can't find any information on where to drain it?

 

Coolant never gets changed on any of my 5 BMW's just to change it. Usually, the coolant never stays in the system more than a couple years before something causes me to drain the coolant to perform some sort of repair. But, otherwise, I would say 4 years is the life of "long life" coolant.

FWIW, on my 2002 Chevy Suburban, I never changed the coolant until the day it was sold in 2013 with approximately 160k miles. Never a problem with that truck...original water pump and all.

 

Some BMW's, such as my 2006 530xi, have a red drain as seen here:
http://www.aaaradiator.com.au/media/...a/aaa-3252.jpg

Later radiators, such as my wife's 2009 X5, seem to have the drain eliminated and you need to undo the bottom radiator hose to drain it.

At least the N52 does not have block drain plugs, so all you get out is what comes out from the radiator. The N52 takes about 2 gallons if you drain the radiator and take off the water pump and thermostat. I buy one gallon from BMW and dilute to two gallons with distilled water. That is enough for a drain/refill.

Be sure you follow the bleeding procedure.

 

Older E60's had a red drain valve on lower passenger side of the radiator. Newer ones don't have that because they have a tendency to leak after just one open and close cycle. Best way do it is to remove the lower radiator hose. You'll get maybe 1/2 and will have to undo the plug in the engine block to get the rest.


You can check coolant condition by using a voltmeter. Ground one end and dip the other into the expansion tank. If you read .4 V or less coolant is still "good".
Not sure about lifetime, but when I checked after 60k it was well within usable limits (.15 volts).