15000 miles
I recommend every 75,000 miles.
60% water and 40% anti-freeze works better than, 50/50, unless it freezes often where you live.
Honda recommends changing it at 100,000 miles. I personally recommend you change it every 75,000 miles. The 2003 Honda Accord had problems with the transmission so I would recommend this as a preventative measure.
Change it every 5 years or 60,000 miles whichever come first.
Every 110,000 miles on the V6 and never on the 4 cylinder.
Every 50,000 miles or 5 years. Read your owners manual maintenance schedule.
I don't know about 2006, in the 2001 it's at 105k miles
On the V6 change it when you change the cam belt. On the 4 cylinder which has a cam chain change it when you have a leak or it fails.
Change it every time you change your oil, 3 months or 3000 miles. Every 40,000km. More often under dusty conditions.
Honda recommends every 100,000 miles.
The official honda's owner manual 1994-1997 says!, once a year i am no mechanic but if its black & sooty change it. common since read your manual.