I don’t fly Gulfstreams any more. To indulge your question though, we didn’t trust the Mx in Russia, so we would’ve never MELed the fuel indications. If we had Mx in Western European countries, we would’ve trusted them more. However, we never had issues with the fuel system. Yes, we had an MEL.
Now, I fly bigger airplanes, as a lot of people do on here, and Mx has absolutely screwed pilots over by either incorrectly sticking the tanks, or not doing it at all. So the original point stands, both in this side topic, and as far as Russia, Mx, and fuel issues.
Also, on Russian flying, if fuel indication problems did happen, most of our flights we wouldn’t have been able to “top it off and send it” due to leg lengths and max landing weight issues.