[Noah930]

I have also always been advised to use Honda cooolant. If you have to top off with water, try to use distilled, instead of tap water (mineral content). Inhaven't done it on our Odyssey, but it was a pretty simple process in our Civic to drain and fill 3 or 4 times for a coolant flush. I did the initial flushes with distilled water, and just used a gallon of Honda coolant for the final fill. I think Honda calls for 100k miles (and each 50k miles thereafter) for coolant changes. You probably don't have to do it immediately, but I'd do it at some point in the near future.