This was taken from Wikipedia, the link is for the rest of the article.
Antifreeze - Wikipedia, the free encyclopedia
Organic acid technology
Certain cars are built with Organic Acid Technology (OAT) antifreeze (e.g., DEX-COOL), or with a Hybrid Organic Acid Technology (HOAT) formulation (e.g., Zerex G-05), both of which are claimed to have an extended service life of five years or 240,000 km (150,000 miles).
DEX-COOL specifically has caused controversy. Litigation has linked it with intake manifold gasket failures in GM's 3.1L and 3.4L engines, and with other failures in 3.8L & 4.3L engines. Class action lawsuits were registered in several states, and in Canada, to address some of these claims. The first of these to reach a decision was in Missouri where a settlement was announced early in December, 2007. Late in March 2008, GM agreed to compensate complainants in the remaining 49 states.
There are rumors that mixing DEX-COOL with standard green (non-OAT) coolant causes a chemical reaction that produces sludge in the cooling system. According to the DEX-COOL manufacturer, however, "mixing a 'green' [non-OAT] coolant with DEX-COOL reduces the batch’s change interval to 2 years or 30,000 miles, but will otherwise cause no damage to the engine."
According to internal GM documents, the ultimate culprit appears to be operating vehicles for long periods of time with low coolant levels. The low coolant is caused by pressure caps that fail in the open position. (The new caps and recovery bottles were introduced at the same time as DEX-COOL). This exposes hot engine components to air and vapors, causing corrosion and contamination of the coolant with iron oxide particles, which in turn can aggravate the pressure cap problem as contamination holds the caps open permanently.
Typically OAT antifreeze contains a orange dye to differentiate it from the conventional glycol-based coolants (green or yellow). Some of the newer OAT coolants claim to be compatible with all types of OAT and glycol-based coolants; these are typically green or yellow in color.
My comment: USE DEX-COOL IN A FORD
AT YOUR OWN RISK!