To refill fluids other than fuel, press on New, select Refill and then press on Other fluid. Select site/section and a unit and press the Next-button. Choose the fluid you want and the amount you are refilling, press on Done and then confirm your choice. Press Save to confirm your refill.
You can add more refills if you like before pressing the Save-button. Press the Refill-button and choose a new fluid and the amount to refill.