I have all my PM racks on and getting ready for a trip to the mountains for 4 days. Just remembered that I forgot to change the coolant. It's been at least 3-4 years. Should I take the racks off to get to the overflow and flush everything out? Overflow is just below the full line but I'm concerned about the age of the coolant.

 

Unless you need peace of mind, it should be fine.
Most modern coolant mixes have anti-corrosion protection for 6 years.

 

That’s kinda what I follow.. the 6yr rule..
unless you have a ton of miles and hammer on it and take it swimming...