The previous generation of Truma gas filters with silver housing draws oily particles, which are carried along with the gas flow as aerosols. If the filter element is saturated (like a sponge which is completely soaked), it cannot absorb any more oil particles. The oil then runs off the filter cartridge and drips into the lower housing part of the filter. Once you notice an oil film there, you will need to replace the filter cartridge.
Previously the filter element with part number 50680-01 was used for the silver Truma gas filter:
As of mid 2020, the filter element with part number 50680-02 is used:
Both filter elements need to be replaced if you notice an oil film in the filter bowl.
