I'm not sure you have a coolant filter. My '06 doesn't have one; the manual might not have been changed. Also, I can tell you from experience with a radiator replacement at 28000 miles that the coolant wasn't damaged. we replaced the coolant at a local radiator shop that did the radiator and they charged me $1.18/gallon for recycled coolant, which they use all the time, and used to recycle themselves. Almost cheaper to replace the coolant at a radiator shop than change the filter.
Former Owner, 2006 36MDDS
2010 Arctic Fox 22GK Travel Trailer
2007 Toyota Tundra