Just went through the same dilemma when they replaced my water pump and replaced the suspect G-05 with a thick green syrup. It's the same thing over and over, nearly impossible, outside of the G-05 realm, to figure out the methods of any given coolant (OAT, Silicate, Phosphate, etc., etc.). Seems as though the Prestones are all licensed and unlicensed Dex-Cool clones. I saw the Toyota coolant at a parts store, but again, the jug gives no info. The dealer that replaced my water pump pointed at the big tank, but knew not what was in it.
Soooo, since I ran the original radiator on my 92 Hyundai out to 288,000 miles on Prestone licensed Dex-Cool, and my experience with G-05 lead me to my first water pump failure ever in any car since I've started driving (not saying the G-05 wrecked my water pump, but a co-incidental first use of G-05 followed up by a water pump replacement 45,000 miles later, I'm not gonna push my luck) I'm going back to the DexCool clone of Prestone. The yellow 5/150 formula in the yellow jug. Gonna drain it and replace it every 18 months, and call it a day. Life is too short to hassle with it.
Irksome to those of us who are curious as to what we put in our cars and can get so little info. Same thing with the Mobil1, same thing with the MTFs, same thing with all the additives. No info. Dump it in, let THEM worry about what's in it, right?