I changed the factory coolant in my 99 EX 4cyl and 02 EX V6 at 60K. In 01 Honda switched to a Type 2 coolant that's supposed to last 10yrs or 120K when filled from the factory. I didn't feel comfortable leaving it in that long, so both cars were drained and refilled with the new type 2 coolant. Honda says when using type 2 at the service interval the newly added coolant should last for 5yrs or 60K and the type 2 is already premixed making it easier to use. I think I am going to change it again between 30-45K even though that kind of defeats the purpose of long life coolant. I couldn't get the coolant drain bolt off so I just drained it from the bottom of the radiator. I figure if this stuff is supposed to last 10yrs or 120K, then what's left in the block at 60K should still be pretty good to be mixed with fresh coolant.