Stink? I don't think he's talking about draining it from a differential and then using it on his guns. Clean and straight out of the bottle it doesn't have much smell.

As for viscosity, it is significantly thinner than any kind off grease would be - at any temp.

Not saying I'm going to use it. Just that I don't see a major issue with it. I'm pretty much of the gear oil for gears and gun oil for guns philosophy myself.