Originally Posted by Roelof

With most kart/bike shops you can find race grade cator oils, I have a liter of Euro Racing-1 at hand when needed as extra oil in the fuel. Other people just buy plain castor at the drug store.

Yes, the meter is a simple 2 dollar ammeter measuring the amps of the electric motor. Because of the pinch the readout is not stable but still it is a good indicator, at the end when the pinch is lower the readout becomes lower and more stable.