Just an update:
I received my GX-Cs4 compressor this past Friday as expected. Unfortunately, my health has made it impossible to test it thoroughly so far.
But it did come without damage and I have filled (topped off) my Fortitude and Akela both from about 2500psi to 3000psi. It actually took about as long as it usually would take me to do it by using a hand pump, but I haven't felt like setting it up in a permanent place where it will be easier to get the fill whip to the gun.
At least in my case, I am happy. I did fill the coolant reservoir with distilled water only. I noticed some soapy looking white particles, so I ended up draining the water and refilling, again with just distilled water.
I looked into using anti-freeze or water wetter, but the more I looked the more I became convinced that pure distilled water will work best for me. The pump is inside and will never freeze and water wetter
seems to simply be a surfactant, but the
ingredients list makes me wonder.
In any case, for me, distilled water is cheap and is better at cooling than any anti-freeze which I don't need with the compressor indoors and I am only filling relatively small capacity airguns.
The gauge matches perfectly with the gauges on my guns and the auto-stop works fine. I still don't know what the second needle is for...???
Anyway, so far I am happy with the compressor. Just not with my declining health situation... (heavy sigh)