Here's why this is a serious problem:
* Internal Combustion Damage: Antifreeze in the cylinders dilutes the lubricating oil, leading to poor lubrication and potential engine damage. The combustion of antifreeze can also create corrosive acids that damage engine parts.
* Misfires: The coolant's conductivity causes shorts, resulting in misfires and potentially damaging the ignition system components. The misfires will also run the engine rough.
* Overheating: A head gasket leak can severely restrict the cooling system's ability to do its job, leading to overheating and catastrophic engine damage.
* Oil Contamination: The antifreeze will contaminate the engine oil, turning it into a milky sludge.
You should NOT continue to run the engine. Doing so will likely cause further, more expensive damage. The head gasket needs to be replaced as soon as possible, and likely a thorough engine cleaning and oil change will be necessary. Ignoring this problem will lead to a much more costly repair (or even a replacement engine).
