Bad Antifreeze???

Frind of mine was heading out to the Fleetwood rally last week. Gets out in the "hot country" and all of a sudden his rig starts to overheat to the point the Cummins (side radiator) started derating.

Apparently he was able to get back to his house and dropped the rig of at the shop.

I was just informed that he was told by the shop that the reason the rig was overheating so severely was due to "Bad Antifreeze"

I have been to automotive school 30+ years ago. Have worked on everything from gas to diesel. I must say, this is the first time that I have ever heard of Antifreeze "going bad".

All prior trips he has had zero cooling issues. So all of a sudden his antifreeze goes bad? Just trying to grasp this one.

Ideas, thoughts?

Thanks all