BMW Repair: BMW 525i thermostat, 525i bmw, bmw 525i

Question
How do you replace a thermostat on a 2001 525i bmw. Is it very hard?

Answer
I haven't done one on this model.  Whether or not it's "very hard" is a function of your skills and ability.  You'll be draining and refilling the coolant, removing the belts and hoses, and likely removing the fan.  If you're comfortable with these, it's straightforward.

If you do the job, replace all the belts while youre at it.