Given this stuff expands as temp decreases, it occurs to me a full system can be more problemmatic for that reason alone
k1vsk, you started out wrong and now you're going deeper
a) "this stuff" is propylene glycol, aka propane-1, 2,-diol, aka methyl ethylene glycol (C3H8O2)
b)The density of propylene glycol (in Fig 7 of the reference I provided), increases as temperature decreases meaning that the volume decreases as temperature decreases. It does not expand as temperature decreases as you stated above.
c)The coefficient of thermal expansion (cet) is positive over the entire temperature range (Fig 12).
dV/Vo = cet * dT/To
As the temperature decreases, the volume of propylene glycol decreases. It does not expand as temperature decreases as you stated above.
There are no problems caused by propylene glycol expanding as temperature decreases, since it doesn't do that.
If you are an engineer, or studying to be one, I am sure there are many things that you know. My advice is that you should stick to writing about those. Otherwise, people may follow poor advice.