Can you please let us know more about your requirement ?
1. Dimensions of the tank (height, thickness of tank wall, diameter of the tank - distance between the walls)
2. Dielectric of the oil
3. Will there be any conductive materials mixed with the oil?
4. Since it is a metal tank, there should not be any direct contact between the sensor and the tank.
5. Since your liquid is non conductive, there is not chance for it getting grounded, hoping that there are no conductive materials that comes with the oil. If this is the case, CSX method should be a good option.
6. In case of CSX measurement, we will be measuring the field lines that goes from Tx to Rx lines. So as the oil level rises, the dielectric between the Tx and Rx electrode increases and thereby the Cm increases. Note that there should not be any contact between the Tx, Rx and the container wall.
Answering your questions:
1. Can you please let me know what material you are referring to here? Is 2cm the thickness of the metal container wall?
2. Yes, you can make the sensor pattern on a FR4 PCB
3. Since oil is a dielectric, it is okay if the PCB comes in contact with oil but since the container is metal, there should be sufficient distance between the electrodes and the container wall. Can you please let us know where the electrode will be inserted? It is better if you can place it in the middle of the container.
4. You can use any height you want. In case of CSX, the capsense performance is independent of the Cp of the sensors. What is the height you are trying to use our technology for?
Above all this, we have our inductive sensing technology too that works with metal overlay. In this case, you can measure the amount of deflection of the metal (container placed above this) as the weight of the container increases as oil level increases.