If you do go with Toyota Red - make sure you put a label on the overflow tank. Something like "DO NOT FILL WITH ANYTHING BUT TOYOTA LONG LIFE COOLANT / DISTILLED WATER".
I took my rig in for an alignment (lifetime alignment at Firestone) and without asking as a courtesy they topped off my overflow tank. With green. Like a month after I had flushed and refilled with "Red Gold", aka Toyota Long Life. Bleh.
Also, when you flush, remember to run the rear heater.
I have lifetime with firestone and also run red. Man, that would drive me crazy. I would have pulled out the overflow tank, emptied and wash out and replace with red asap and hope the red and green didn't mix too much. Knowing my ocd, I'd probably flush all over again.
You sure gave me something to think about next time I go there for alignment [emoji1]
OP.... I paid the dealer to flush my red and refill with red, and since that time I only do drain and fills on the red (have to mix the red yourself with distilled water, 50/50)
For what it's worth, they supposedly had a tank with hundreds of gallons of red and a hose. They flush the radiator/block/etc with the hose before filling with red. It wasn't that cheap either, but I don't plan on doing that again.
I didn't witness the tank obviously (being in the waiting area), so I can only hope I wasn't lied to
The only other way is to flush yourself at home with distilled water as someone mentioned earlier, and NOT a garden hose with tap water.
Red vs green is one of the many forum debates..The best way to deal with it if you can't make a choice is whatever you choose, regular maintenance is key as rock rat stated above, and more important than the arguments.. .regardless of topic (diff fluids, dino vs synthetic oil, etc).
I hope that helps.
Good luck