OP posted that the replacement stud has a notch cut out in order to fit in. What else is in the way, the small bit of backing plate that hasn’t rusted away yet? Cut or bend it. I doubt the knuckle would be in the way

Grinding the head of the stud would be enough I bet. Super quick and easy. Removing a cotter pin and a nut will leav OP very far from being able to complete the job

What’s the welder for…?

You’d need a refractometer to really know the ratios. Book listed capacity and real world how much fluid it actually needed to be full are two different things. Your “mechanic” owes it to you to get more equal or better coolant and re-do the service.

Sure isn’t fast

Your charcuterie board is getting too full.

Jk, this is a diesel thing and IDK.

It’s an equinox, these things are known to have issues. There is enough info available that I would feel no reason to disclose anything during a sell. I would consider this normal operation for the vehicle, more or less. Definitely can’t feel bad if you decide to sell to a dealer as a trade-in on a new ride.

Looks like normal operating temp depending on vehicle. Some are at different areas on the gauge at normal operating temp. My 01 tacoma stays exactly at halfway. QX30s are at about 2/3 normally. Need a known good comparison to judge. Doesn’t look like an issue to me.