I have a 2011 5.0 xtr which I'm going to be doing a engine coolant flush on now it's 5 years old. What is everyone's thoughts on changing the thermostat whilst I do the flush? Would it be something worth changing? Or is it something unlikely to go faulty in the future and not worth changing if it's not broken?

 

cheap and easy, why not? especially if you are doing the flush yourself.

 

I hate changing something when it's not broken, but I know thermostats do go eventually, and I don't really want to change it after I have already done a flush. Like you said, no harm in it.

 

Are you ready to lose about half your coolant when you have to change a $10 or 15 dollar thermostat?? Plus the coolant & your time to replace the thermostat and gasket??

Of course, it's not gonna go out in your driveway, it'll stop working when you're on vacation with the kids and the truck loaded up, and 200 miles from home in the wilderness....

Pretty easy decision, IMHO...