Oil gauge was bouncing to the left & to the right. Now the gauge is at the 3 o'clock position. The truck runs & I have oil 161,000 miles & I change the oil every every 3,000 miles.

 

bad gauge?

 

pegging at the top generally means you have a short in that circuit somewhere. find the sensor and disconnect it. if the gauge still pegs, it is a wire, otherwise the sender shorted internally. Low gauges usually mean the sender is not doing it's thing or is broken

BTW verify that the thing isn't actually correct by checking it with a known reliable mechanical gauge.