Insignia Coolant Loss

Low coolant on a '22 Insignia diesel...hmmm. Radiator fluid disappearing without a trace is never fun. Are you seeing any white smoke from the exhaust, or any signs of coolant mixing with the oil? Just trying to rule out a head gasket issue early. Also, any staining or crustiness around the radiator itself? Sometimes, tiny leaks can evaporate before they become obvious.

No white smoke or milkshake oil, thankfully. And I've scoured the radiator fins – nothing obvious, though I suppose it could be a pinhole leak somewhere. Given it's a '22, could it be something simple like a faulty radiator cap not holding pressure, causing slow evaporation? Or am I being too optimistic?

A faulty radiator cap is possible, but unlikely on such a new car. Given the lack of external signs and no oil/coolant mixing, it's difficult to pinpoint remotely. I'd suggest a pressure test of the cooling system. If you aren't equipped to do that yourself, taking it to a workshop to get it checked is advisable.

Cheers for the sanity check. Knew I was probably hoping for too much with the rad cap. Bit the bullet and took it in. Turns out it was a leaking hose clamp that needed tightening, and they topped off the coolant. 52€ all in. Sorted!