My local Honda dealer sells a gallon of Type 2 for around $18 and it's what I've used in my old Accord for over 15 years. I'm sure another suitable coolant would be fine as well, but I can tell you the insides of the engine coolant passages are pristine as well as what you can see in the radiator through the pressure cap. I change it out every three years or so via a drain-and-fill.
