OK…Here’s part of the problem…The PepBoy mechanics work on commission. The mechanic was probably trying to drum up business. I’m really at a loss how the mechanic was able tell by visual inspection that you have a broken head gasket. You can’t even see the gasket…it’s sandwiched between the head and the block.
Take it to a TRUSTED independent mechanic. This story is getting shakier and shakier by the minute.