2G Oil pressure gauge acting up or something worse

[ttravis88t]

My oil pressure gauge dips whenever I use something electronic. Such as pressing brakes and making brake lights come on, same for when I turn on the AC (car has no ac so just the fan) also rolling up windows, turning on headlights, pretty much anything causes it to drop. Sometimes in traffic it’ll even go below ZERO which is pretty damn scary. What can be causing this and I’m sure these things aren’t actually affecting my oil pressure? (Video attached)

 

[ttravis88t]

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[DSMPT]

Was it working fine before or you just installed it? To me, it looks like improperly wired, like taking a wrong constant 12v or you have a voltage drop for some reason, maybe a weak alternator/regulator or battery. If you are not taking the constant 12v from battery, try to take it directly from battery and see if it would make any difference.