If it's not leaking (either externally or internally), then I suggest that you do not leave the water in the car w/o some additive. . . . it will corrode quickly.

But I'd follow your suggestion about doing a good flush. Now is the time.

If a heat gasket blows, it's most likely internal . . a small leak into the cylinder, mixing w/ the oil to make a chocolate milk shake that you can 'drink' from the overflow resovoir. Let's hope that there's none.

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Regards . . . . JimF
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'94 S500 Cpe

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