Just thought I'd share some expert testimony from the Dexcool lawsuit recently. Here is a link and quotes. Happy reading !! http://www.imcool.com/articles/antifreeze-coolant/dexcool2007Part3.php "Expert witness: DEX-IMG incompatibility well-known One of the documents is from a 50-year veteran of the gasket and seal industries. A member of the SAE, ACS (American Chemical Society) and ASTM, the latter of which he served on the D15 coolant committee, he states that he was aware of GM’s 3.1 liter, etc, IMG failures well before learning of the lawsuit. He goes on to say that the gasket’s poor design and incompatibility with DEX was well-known in his industry. What brought up the discussions was GM’s adopting DEX in 1996, which of course led to widespread testing by him and peers. Those companies included heavy duty manufacturers Caterpillar, Cummins and International. He authored two technical papers, derived from thousands of hours of testing, focusing on the effects that DEX’s corrosion inhibitors have on rubber and plastic gaskets and seals, including GM’s IMGs in question. He concludes that the two are incompatible because DEX OAT inhibitors degrade both silicone and nylon, of which these gaskets are made. For more specifics, the IMG is described as Nylon 6,6 carrier, 33% glass filled, injection molded, single silicone sealing bead. This man felt the IMG was not a good design to begin with, and then the inhibitors start attacking the weakened carrier. Evidently, because the silicone sealing bead is not molded over onto the carrier, the carrier is in direct contact with the DEX. Tie that in with no compression limiters, needed to maintain gasket integrity (see photo above), to begin with and that, according to the expert, is why the gasket is prone to fail. Expert witness: HOATs do not degrade gaskets Interesting, this expert witness went beyond the DEX problem to clarify that different from DEX OATs, HOATs, Hybrid Organic Acid Chemistry coolants, do not degrade silicone and nylon gaskets. The explanation is quite simple; the added silicate inhibitors of the HOAT protect the silicone polymer from the type of degradation it suffers with pure OAT (DEX). (I think I need a Chemistry refresher.) Expert witness: IMGs should not fail As another expert witness, the plaintiffs brought in a long time, highly experienced Certified Master Technician who has completed 2000 hours of formal diagnosis and repair training. Along with providing diagrams of the engine components in question, he testified that IMGs normally do not fail on their own; they shouldn’t need replacing unless you’re repairing or replacing an adjacent component. Their failure rate should be zero and he’s never seen just an IMG fail. For this engine, to replace them is a 4-6 hour job and will cost $700-1000."