Our hydrostatic pumps that we used to use to test watermain for leaks used glycerin filled guages, we tested watermain whenever we put it in, summer, winter, whatever. The pump sat in the back of the truck, sometimes for days at a time, in even below zero actual temps. The guage remains fine. My only recommendation is that they sell guages that go up super high, while it will still work, you won't get the accuracy of one that only goes up to say 30 pounds, the increments are larger and easier to see. Grainger would have them for sure, or even any good plumbing supply. And yes, you can walk in off the street, and wave cash around, and they will sell to you.