Check in your owner's manual for specifications for the coolant and then find a name brand which meets them. I notice you mentioned "red". Could be that a Canadian thing? Ours is "green" (or maybe yellow, I guess) but if you can match the JIS, SAE, or ASTM number(s) listed in the manual, you will be just fine.
I do notice that most manufacturers have stopped listing the numbers on the container (must confuse the users) but you can find them on the web site for the product in question. Try Texaco, Havoline, or Prestone sites. We just used Prestone Extended Life Antifreeze/Coolant which matched the specs in our manual. If you don't mind doing the mixing yourself, it is generally cheaper in the long run to buy the concentrated containers. They charge a lot of money for the water and the convenience of just pouring it in. Distilled water is recommended for the mix.
And the difference in price, especially if there is a WalMart or equivalent in your area, would make even a flush-and-replace a deal, let alone having a ready source for topping up without worrying about mixing brands again. However, my (limited) knowledge says if the specs match, they should mix OK anyway. I have seen arguments both ways and only am guessing at that knowing how specs are set by the various organizations.
There should be no effect on warranty provided you can show that you used equivalent (i.e. matching specs) for oils and coolants.
