Dexcool coolant

I know some of the older GM vehicles had compatibility problems on some of the engines that were supplied from the factory with DEXCOOL, the coolant would attack certain gaskets causing leaks.
Jeff

Just did the coolant change using DEXCOOL again, and after about 4 years with no coolant change, the coolant that came out appeared just like new. I know I don't drive the car that much, just to shows, to work, cruisin PCH by the beach babes, and just around da hood, but I thought the fluid would at least be a little dirty. Plus I drained from the radiator plug and also from the tubes under the car. I was surprised to see how much more fluid came out of the car by draining at the underside tubes after draining from the radiator. So I guess it is good to do both.

These days it pays to do some checking. Since about 1990- thanks mostly to Honda, there have been anti-freezes specially formulated for ALUMINUM engines. Prestone-yellow and others of the type have silicate grinding compounds in them to scour scale from iron engine castings. Silicates do this but also attack the sliding main seal inside your waterpump. They also scour aluminum castings much faster than the iron they were intended to affect, enough that long-haul trucks with alloy engine castings have had failures attributable to silicates.
Nowadays, antifreezes come in yellow, green, orange and who-knows-what color. I suggest if you have an all-aluminnum engine & radiator (like Jan) or mostly aluminum (like me), look for the type made for alloy engines. This included motorcycles, incidently. The 'new' antifreezes are more expensive but who really wants to irreversibly erode an alloy block, heads or radiator?

Yes, in respect to the nonDEXCOOL type, in my other aluminum block cars I use the prestone longlife, because that is silicate free too. Only reason I go with the DEXCOOL in my group 4 is that I hear all over the web that you should not interchange the two fluid types once you start with DEXCOOL or the other, unless you are able to flush the entire contents of either fluid out first before switching. As far as silicate, this below is what the prestone website says:

Q:
Does Prestone® Antifreeze/Coolant contain phosphates?
A:

Some European automobile manufacturers request that a phosphate-free antifreeze be used in their vehicles. This issue is related to the extremely high mineral content of the water in Europe. If you were to mix an antifreeze that contained phosphates with the type of water they have in Europe, it may produce deposits that can settle in the cooling system and promote corrosion. However, in North America we do not have this type of water problem. Typical North American coolants have contained phosphates (which is part of the corrosion inhibitor package) for many years. Therefore, the question of phosphates is a non-issue here in North America. Prestone® Antifreeze/Coolant is completely safe for use in both foreign and domestic vehicles. For those consumers who would feel more comfortable using a phosphate-free antifreeze, our Prestone® LongLife® Premixed Antifreeze/Coolant and Prestone® Dex-Cool® Premixed LongLife® Antifreeze/ Coolant formula’s are phosphate, silicate, and borate free. These coolants use a special chemistry and technology that extends the life of the corrosion inhibitor package so that it lasts for five years or 240,000 kms (whichever comes first), and is safe for all cars and light trucks (old or new). Prestone® Dex-Cool® Premixed LongLife® Antifreeze/ Coolant has been approved by General Motors under their DEX-COOL® specifications and is compatible with other DEX-COOL® approved coolants.
* DEX-COOL® is a registered trademark of General Motors Corporation.