Overheated and died while driving on the highway

Do a compression test on all cylinders before continuing.

As I was about to do a compression test, notice coolant leaking from the muffler and not the tail pipe. Appears that a compression test will not repair this. Do you think still worthwhile to perform as it appears to be a head gasket issue? Hopefully not more. Any additional guidance before locating a mechanic to repair.

I would still do the test. It will not repair it it just test for compression leak. It can help you know for sure which or between which cylinders the leak is and you can be more able to locate other issues like a crack if one in that area or surface scars ect, it may not be the gasket, it could be cracks. I would want to know where its leaking or not and if that coming out muffler is for sure coolant and not condensation as all can produce.

I am certain fluid that is leaking from muffler is coolant. Bright green. Attempted a compression test on 1,3,5. Pressure for these three was 40, 0, 0. As I was doing this also noticed large oil leak under the engine. Is this an additional indication that the block is cracked. Looked at the oil not milky. However, noticed that it is way above the fill line. Thinking coolant is leaking into there as well.

Sure sounds like a new engine. I will say that the oil passageways also run threw the head gaskets but if you getting a large puddle of oil from somewhere other than a gasket, may just be a crack. The oil level higher than normal, the two fluids resist mixing and would take some engine running time or a whole lot of coolant and some run time to turn milky, its likely coolant in bottom of oil pan.