GX Overheating Slow Warm Up

I also own a GX. Overheating and slow warm-up can certainly point to a thermostat problem. I've seen similar behavior when the map thermostat malfunctions. Have you checked your cooling fan operation or looked for any coolant leaks?

Thanks for the quick reply! I haven't checked the cooling fan specifically, but the coolant level seems fine. What exactly do you mean by 'map thermostat'? Is it different from a regular one?

The map thermostat is an electronically controlled thermostat. When it fails, it often gets stuck in one position, causing the symptoms you're experiencing. Given the symptoms, and my past experiences, I suggest having a workshop check the thermostat. That's what I did when facing similar issues. I got it fixed for 350€

Okay, that's really helpful. I appreciate the advice! I'll get it checked out by a professional. Sounds like the thermostat is the likely culprit.