Isn't that what DexCool (aka DeathCool) coolant looked like in GM cars when it was drained?
Kymco says they use DexCool-rated coolant in my scooter as factory-fill, I'm assuming they use the same in all of their scooters... and yet we don't see this sort of problem.
Does Sym use DexCool coolant?
From my antifreeze analysis:
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http://www.kymcoforum.com/index.php?topic=3649.msg97448DEXCOOL NOTE:
DexCool is not a specific formula, it just denotes that the anti-freeze product passed GM's testing requirements. All three brands that have the label (Texaco Havoline, Prestone Extended Life and Zerex Extended Life) are somewhat similar. In particular, they’re OAT (Organic Acid Technology) coolants. All DexCool-approved coolants to date use two organic acid rust/corrosion inhibitors, one called sebacate, the other called 2-EHA (which stands for 2-ethylhexanoic acid).
POTASSIUM 2-ETHYL HEXANOATE:
DO NOT USE THIS INGREDIENT! This is an OAT (Organic Acid Technology) ingredient. If the least bit of air gets into your system, it will turn into a rusty-colored sludge that will plug up coolant passages (i.e.: Dexcool used it, and has gained the nickname 'DeathCool'). Your coolant expansion tank will sludge up, since it is exposed to air. OAT anti-freeze ingredients take a long time to lay down a protective layer of metal oxide (the passivation layer) to protect the metal. Hence, if your water pump is cavitating and exposing fresh metal (as I suspect ours do, with the high RPMs developed), OAT will not work quickly enough to protect it. The result will be a badly corroded and eroded pump impellar. This was not listed on any of the anti-freeze products I looked at, but is known to be used in some Dex-Cool anti-freeze products.
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I've found Zerex Asian Vehicle is the most-compatible coolant on the market for our scooters. I looked at pretty much every coolant out there, all their ingredients, did tons of research on the effects of the ingredients upon the metals in our scooters and how those ingredients age, etc.