You should avoid Dexcol which is orange or pinkish and the old “green” antifreezes. The yellow long life antifreezes from Prestone, Peak or Zerex are essentially the same as the coolant that is in it now. Since most of these are around 410/gallon, you could check with the Mazda dealer for their price. A couple of bucks extra every 100,000 miles might be worth it for your own peace of mind if you are unsure, but I would not be afraid to use any of the yellows available, mixed with distilled water. I prefer to mix 2:1 antifreeze/distilled water, but most people use a 50:50 mix.