But, running ANY engine when it’s low on organic acid type coolant cause form sludge.

The “rusting” usually does NOT affect newer aluminum engines. When cast iron engines run low on coolant, the organic acid technologies oxidize and cause iron oxide deposits. But after a thorough investigation, it turns out that the only time sludge builds up is if the engine is low on coolant.

Specifically, shops reported sludge buildup, especially in cast iron engines. Shops reported other problems with DexCool engines besides the 3.1 and 3.4-liter engine. So contrary to the ranting, DexCool IS the recommended coolant for GM engine. GM still uses Dex-Cool coolant and there is no longer a problem with gasket coolant interaction. GM has since redesigned the gaskets that the problem has now been fixed. Everyone assumes the problem was Dex-Cool, when in fact, the problem was the type of gasket material combined with the use of Dex-Cool and reusing the old intake bolts. So it’s true that DexCool caused gasket leaks, but the real problem was incompatibility between the plastic and the coolant. The bottom line is that owners sued GM in a class action and won a settlement to reimburse them for the gasket failures. But the shops would never admit to their mistake and blamed the coolant. So if you don’t use new bolts and follow the torque directions TO THE LETTER, you’re going to get another leak. The problem with the newer plastic gaskets is that they’re fairly low torque (because they’re plastic). Wrong! Dex-Cool wasn’t the cause of the leaking gaskets

At the time, many shops re-used the old intake manifold bolts with the new gaskets and then re-installed DexCool, only to see the gaskets fail again. The repair involved pulling the intake manifold and replacing the gaskets with a re-designed style. The problem was so extensive that it affected just about every 3.1 and 3.4-liter made in the late ‘90’1 and early 2000’s. For some reason (and NO ONE agrees on why this happens) the gasket material and Dex-Cool interact with one another, degrading the plastic gasket and causing leaks. At the same time, GM also started using plastic intake manifold gaskets with a silicone bead around the ports. That’s when GM introduced Dex-Cool coolant, an organic acid coolant technology (OAT) to replace silicate coolants.ĭex-Cool, like other modern coolants is about 95% polyethylene glycol and 5% organic acid.ĭex-Cool is rated with a 5-year, 100,000 mile lifespan. When car makers switched to aluminum engines and radiators and away from cast iron components, they also switched to long-life coolants. Second, the passivating feature doesn’t last very long -max 2-years or 24,000 miles. First, it’s somewhat abrasive, so it’s tough on water pump seals. With both conventional and DEX-COOL(R) coolant.There are two problems with silicate. It. The green DEX-COOL(R) appearance is caused by the color of the leak detection dye which alters the color of the DEX-COOL(R) coolant.Ī new leak detection dye P/N 89022219 (J 46366) (in Canada P/N 89022220) has been released that does not alter the appearance of theĭEX-COOL(R) coolant. When adding the new leak detection dye the color of the DEX-COOL(R) coolant will not change. For detecting leaks on any Leak detection dye P/N 12378563 (J 29545-6) (in Canada P/N 88900915) may cause DEX-COOL(R) coolant to appear green in a black vessel making itĪppear to be conventional (green) coolant. This may cause a technician to add conventional coolant to a low DEX-COOL(R) system thus contaminating This bulletin is being revised to include additional model years. Please discard Corporate Bulletin Number 05-06-02-002A (Section 06 . *EXCLUDING 2006 and Prior Chevrolet Aveo, Epica, Optra, Vivant and Pontiac Matiz, Wave

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