I'm a little concerned about the accounts of casting porosity in the 6 cyl block or head. This would certainly explain it. No external leaks, no

WP seal or gasket leaks, heater core seems OK (no smell in car, no coolant in condensate drain) no coolant indications in engine oil or ATF. Runs fine so far. Could it be leaking outboard of the exhaust valves and vaporizing in the manifold? I assume this would kill the cat or O2 sensor after a while. But no white smoke shows.

Coolant has to be going somewhere and it is doing so at the rate of about a pint a week. In winter. Perhaps more. This engine would fry and bend like a hot dog if it ever got seriously dry.

Any ideas? Has Volvo ever done a TSB or adjustment re the casting problems? Who would know? Mayday, Mayday!