[fwayne]

Man hope you lucked out. I pulled a similar stunt back on my teens working on a Slant 6 Dodge. Little old lady car...supposed to change oil and replace vacuum lines. As I was warming it up and just finishing the vac lines I saw my 5 quarts of oil sitting on the bench...I had run the engine for about 10 minutes with no oil at all. Being the low man on the totem pole and needing my job, I poured the oil in, and that car came back for years for routine maintenance without ever knowing. Man those slants were tough!

BTW Ive personally had it go both ways. Core plugs pushed out and the block wasn't cracked once, and on another it cracked between each core plug.

The guys are correct those plugs are just freeze evidence, not freeze protection. Luck is a better factor.