Yeah I got there as well, and it’s is a possibility. Last year I put in long life presumably HOAT for Mercedes some Canadian Tire brand that they no longer sell. This year IN AUGUST when I did my waterpump, the Canadian Tire brand is no longer available and a new brand was on the shelf OEM brand, Euro 1 the full strength supposedly for MB. There’s was no HOAT written on the container but I trusted they were not bs ing me. Looked it up online turns,out it is OAT!
So I may have mixed OAT and HOAT (but only 10-15% as i drained the system pretty good during waterpump as i had to do the Ac condeser in the cooling pack)
I would be surprised if 10 months of OAT or 2 months of 15% HOAT/85%OAT would cause a seal to fail, but I’ll know soon.
I’m a bit pissed that the OEM Euro 1 is not HOAT as it clearly states on the front that it is for Mercedes, and from what I can tell Mercedes has been using HOAT for the last 15-20 years.
I have written CT and OEM, and obviously a full flush (possibly chemically flush) is in my future.
Flushing the engine in the winter is less than ideal as well.
The whole long life coolant thing is pissing me off. Seems I crack into coolant systems at least once every 3 years with older vehicles, maybe universal coolant is the way to go, less bs, just change every three years or when servicing.
Live and learn.