i only run Toyota pink and it took forever to flush the coolant from the po. I don't think this has anything to do with your leak but when i replaced my water-pump i read a lot of horror stories about some types of coolant having a reaction with some internal components. The toyota pink is...
How old is your radiator? The 99 might be different than yours but the top of the radiator housing can sometimes steam just a little bit under pressure. might not be bad yet, but if that's it i would def replace asap. I found rock auto had great prices and they actually had them in stock. I hope...