Radiator Flush

[Puggsley2]

My 2005 E85 Z4 has not had the coolant changed for many years and the service manual that came with the car makes little mention of it. How often should the coolant be changed and am I risking damage if I use after market replacement fluid?

 

[Chris_D]

It's a good idea to replace ur coolant at least every 20k miles as any fluids can deteriorate and become less effective.
Just done mine and following a thermostat and waterpump replacement has solved an overheating problem.
Think about replacing the waterpump too.

I flushed and replaced 5L using Kroon P11. Was led to believe I needed 8.5L