I remember years ago working on V6 Volvo who used a Renault v6. The casting was very thin near the
oil galleries. Then when the cooling system wasn't maintained properly, it would corrode into the
oil gallery and fill the entire cooling system with high
oil pressure. Destroying the radiator, heater core and a hell of a mess to clean up. Just removing heads was tricky, if you bumped the sleeve it would break the paper gasket at the bottom of the sleeve.
JD