For reference: This is a 2012 G37 Sedan with 230K kms on the clock (143K miles) that was always serviced every 10K kilometers (6K miles) at the dealership.

4 months ago the dealership stated that the coolant system was leaking and I decided to repair it at a local mechanic, he changed the expansion tank, upper/lower radiator hoses and the thermostat.

A couple of days ago I had the car start overheating on the freeway and pulled over. The reservoir was almost empty so I topped it off with distilled water. It cooled down and then started doing it again after a while so I had it towed to a new garage nearby. They stated that there is a major coolant leak and some minor oil leak.

They quoted:
Thermostat assembly, water inlet gaskets, water outlets, radiator cap, hoses, o ring seals, reservoir tank hose, water pump assembly for the coolant leaking and a bunch of other seals for the rocker cover, solenoid and crank shaft for the oil leak..

They sent a bunch of photos to show it (next post)

The quote was quite expensive and because the coolant system was leaking again, I sent it to the same mechanic I had the coolant system repaired with earlier. He stated that the coolant system leaking is a secondary issue and that the main issue is the head gasket. Apparently the coolant is leaking between the block and the intake manifold and because the car was driven while it was leaking, the engine might be damaged and he has to take the intake manifold off to inspect the pistons for damage, the head gasket for damage and the block for rust damage.

I am skeptical that the head gasket is damaged because the oil does not seem to be milky or mixed with water. There also does not seem to be any sweet smell from the exhaust, (but the engine bay smells like **** xD). There is an inspection fee to take apart the intake and inspect but I would much rather not have the engine taken apart if it is not necessary.

Any suggestions?

 

https://imgur.com/a/hWTvJ6o

Photos from the first garage's inspection and the oil after I had it towed