He did ask about warm cold ...

About the IM gasket The 5L gm's of that era had a corrosion issue with the gasket. I think the Olds 307 was the worst. I think they were aluminum? And that manifested in a coolant leak into the valley and cylinders. any coolant loss? IIRC the corrosion/leaks were usually at the rear on the driver side of the motor.