I've heard lots of people say that its best to use the "red" coolant that you would buy from the dealership. From my experience I would say not to. But that's only my opinion. Here's why...
I was changing the T-belt the other day and realized my water pump was corroded with what looked like a red substance that dyed the metal around the pulley ASWELL. First thought was did the red engine coolant eat through the metal of the water pump? After doing some research and talking to a couple mechanics, they confirmed what I was thinking. Basically what I was told is that after long use of that red Toyota coolant it corrodes metals other than the engine block. The block is strong enough to withstand the red coolant. But with the metal that is on the OEM water pump isn't. Eventually it will start to corrode and cause problems unless caught early. Mind you this is the first time I've changed the water pump and its a 2001. So about 12-13 years of using the Red coolant from Toyota will start to corrode some metals that it comes in contact with. I also heard the "pink" coolant that's out there will do the same.
All the is from my own experience and research. It's only my .02
If anyone else has had this problem with the use of Red coolant let us know.