I suspect that the reason for the de-oiling is to reduce the amount that the acid is neutralized by the residual coolant in the system.

That being said, I can't see how a soap (de-oiling agent) would do that much to neutralize the acid. Better to wash through a mild solution of baking soda during one of the first rinses, if you're truly worried about it.

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-Josh
Testing the cheap Mercedes axiom, one bolt at a time...