I know this is a much debated topic but I need to know what's best to use. See someone mixed green and red in my cooling system. There is green in the radiator and red in the holding tank. Should I drain it and fill with red?
In fact, I finally decided to stop listening to all of the "experts" and research this one myself. Here are a couple of highlights (of many, boring details...)
1. Color has no bearing on the formulation. The manufacturers add color for distinction, for marketing, and perhaps because of the phase of the moon;
2. The additives in each type are usually different, and therein lies one of the major problems, or solutions to coolant issues;
3. Mix different additives, as Beo says, and they can (and often will) precipitate out of solution into various forms of pooky and grungus that will play havoc with the cooling system over time;
4. The Toyota (so called, "Red") has NO borates, and very little silicates... and in that respect, differs considerably from some of the others (yellow, green, etc). Just how much this matters is what forms the basis of the great debate;
5. If you subscribe to the theory that Toyota engineers know what they're doing, then you will probably opt for the Toyota Red;
6. Whichever you use, be sure to do a really thorogh flush, not just a simple draining, use only distilled water... and the general wisdom of the sages is to NOT use the organic acid technology (OAT) types of coolant, since 1FZ-FE was not designed for it.
I heard red will last a lot longer w/out risk of corrosion. Never mix green and red. Some chemical reaction goes on that clogs up the radiator...happened to my 4Runner..forgot to turn on the heater when running the engine, so the coolant in the heater core was green while that in the radiator/block was red. I used distilled water. Sure, it was the original 2-row core radiator w/ 100K mi on it, but had been working fine up to then. Soon afterwards, upon starting up the engine and pulling out of the parking space, I started hearing sounds like water flowing through pipes in the walls of a house when someone flushes the toilet. Radiator was 60% clogged. Bought a 2-row core CSF replacement....piece of junk. Sold it and replaced it w/ a 3-row core Modine...so far, so good. There's green in there now, but I plan to switch to Toyota coolant this summer. I hear Toyota/honda coolant lasts years. I guess that's how they come up with those ridiculous coolant changing intervals of 60K or 100K miles in the FSM.