by Mr Ree » Tue Dec 11, 2012 8:43 am
And some more info...
The red or pink coolants are made for aluminum radiators. If yours has copper/brass/bronze parts in the cooling/heater system, you're better off with the green coolant because the red/pink will react with those parts and causing blockage and subsequently, overheating. Bottom line… use Toyota (OEM) red to protect metal and seals. Use de-mineralized or distilled water. Minerals dissolve into scale that clings to metal and clogs radiator passages.
"Genuine TOYOTA Pre-mixed Anti-rust Anti-freeze / Super Long Life Coolant is a new generation ethylene glycol-based premium engine coolant, offering excellent corrosion protection formulated specifically for all TOYOTA warranty requirements. For vehicles fitted with Super Long Life Coolant at the plant, it is highly recommended that Super Long Life Coolant be used for maintenance."
-This is for the Toyota Factory Pink Fluid part number 08889-80071
Toyota Red uses a phosphate anti-corrosion chemistry. The green stuff uses silicates. Both are inorganic chemistries, but they are incompatible. Phosphates do especially well with iron, and do fine with aluminum, and with copper/brass/lead radiators and heater cores. All Japanese carmakers prefer phosphates.
Silicates (prestone green) are particularly good with aluminum, not as good with iron, and do fine with copper/brass/lead. They are slightly abrasive, and are slightly more likely than phosphates to cause leaks in water pump seals. European carmakers prefer silicates.
The problem with phosphates in particular is that they are the least compatible chemistry - mixing with the minerals in tap water or with a different coolant type will cause the phosphates to precipitate out and clog radiator passages, while at the same time your corrosion protection goes bye-bye.
But both inorganic chemistries must be replaced every two years because the corrosion protection wears out.
Then there came a new type, based on organic acids (so-called OAT types), such as most of the new long life coolants like Dexcool. These are a bad choice for older vehicles because they will corrode copper/brass/lead radiators, and because the OATs react very strongly and harmfully with the inorganics.
In an attempt to address that issue, there came a new type called "Hybrid Organic Acid Technology (HOAT). Those include your Prestone yellow, Zerex G-05, and the new Toyota pink (though that is somewhat in a class of its own). The HOATS combine an organic acid (different than the one in DexCool) with inorganic inhibitors. All the HOATs use silicates except Toyota Pink, which uses phosphates. That's why Toyota says it's okay to mix pink & red.
I stick to Toyota Red and not the pink at all because my MKIV TT is a 1994. I like to be on the safe side and not take the chance with an investment as large as my Supra. Plus the Toyota Pink is a pre-mix and I don’t want to pay for a half jug of water.
Theoretically, the HOATs are okay to mix with any coolant, but I think only time will prove whether that's true, and I think it is foolish to test their theory in your engine. I remember DexCool was hyped as a cure-all when it came out too. HOAT chemistry is still acid-based, and for that reason I think you probably don't want to use them in an older vehicle that has copper/brass/lead radiators and heater cores. That goes even for the Toyota pink. Both the OATs and the HOATs were designed for aluminum radiators and heater cores.
If someone doesn't know what type of coolant was in their motor, they should FULLY flush every spec of coolant out, which can take six or more flushes. Be sure to open all the drains (including the one on the block if you can get at it) and make sure your heater temp is all the way to hot to enable the coolant to be washed out of the heater core, too… it also helps to remove the thermostat on most motors.
As far as the proper coolant to use, I recommend what Toyota designed for the motor: Toyota Red coolant. Mix it 50/50 with distilled water. Don't under any circumstances use an OAT coolant. Some will say HOATs are okay. I think that assertion is iffy, and anyway it is unproven. Many will say green silicate-based coolants are okay. But Japanese car makers intentionally never used silicates in their engines - they used phosphates instead. Why not use the coolant that was designed for your engine? It's not THAT expensive, and you only have to change it every two years.
wak thud gush!