Sludge appearing soon is an indication to me that it was already there,
just stuck down in the block.
I've seen some pretty murky stuff in the company vehicles, but that was
DexCool, not G-05.
Any time you change coolant on a vehicle with unknown maintenance, I
would recommend a citric acid flush (fill with 10% citric acid and run
till fully hot, cool and then flush till it's clear) --this will
dissolve all that rust and carbonate sludge that has collected.
I also recommend using at least low mineral content, if not distilled,
water with G-05 (pre bottle recommendation) -- hard water may cause
tons of crap to precipitate.
Peter
