This winter was extremely cold.  We had many days of deep freeze and the temperatures went as low as -30c.  Luckily antifreeze is effective at this level of coldness, right?

Well, maybe not.

We left 2 jugs of antifreeze in the van.  They were sitting side by side in the same location for the same amount of time, and were exposed to the exact same conditions.  Absolute Zero (Propylene Glycol, non combustible) promises to be effective up to -60C and Winter Tech (ethanol, combustible) up to -46C.

This is what we discovered today.  Absolute Zero seems to be fine and completely liquid.

while Winter Tech turned into a thick slush.

The good news is that slush is not solid freeze, so there may not be any reason for alarm, but still it doesn’t seem to be right.  We did use the Absolute Zero brand to pour into the veins of the van last time we winterized, so we are hoping that when everything thaws we won’t have a mess on our hands.

A quick Google search of RV antifreeze shelf life revealed the following:

• according to some, RV antifreeze has a shelf life of at least one year if kept in its original packaging;
• others stated that they used RV antifreeze that was sitting around for several years with no ill effects;
• yet others claim to recycle the same antifreeze year after year (this is extreme frugality that can cost you more in the long run, in our opinion).

We went to take a look at the bottles and there is no expiry date on them and no indication that there is any time sensitivity, so we assume the slushy bottle is not “expired”. 

A bit more research revealed that Propylene Glycol does turn into slush in very cold temperatures, but would still protects your plumbing, so perhaps no need for alarm.  Oddly, our slushy antifreeze is the ethanol one, while the Glycol remained liquid (it is rated for colder weather though).  It looks like we don’t have a clear idea of what is going on, but it may be normal for antifreeze to freeze.  Who knew.

Perhaps next winter we’ll line up a few more kinds of RV antifreeze and compare the results, however, we are hoping that it won’t be so cold next year, or better still, that we’ll be somewhere warm.

In the meantime we’ll consider using vodka instead of antifreeze, it doesn’t have a shelf life, and we won’t mind the after taste either!

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