Starting from the top,
If the speedo needle moved smoothly and didn't bounce, it's likely fine.
+/- 15 degrees on that gauge is probably well within the original spec.
Test only tells you the winding is intact. connect it in series with a good gas tank sensor or a variable resistor of the same range as the sender and a battery. Changing the resistance should move the gauge in scale.
If it is a volt meter attach it to a battery and check the reading with another volt meter. If it's an amp meter, connect it between a battery charger (set for less than the scale of the gauge) and a battery and check the reading.
oil gauge sounds about right, but checking with a calibrated pressure supply would be more accurate.
