(Graph Presented) The long-term stability of a dye-sensitized solar cell (DSSC) is a key issue for upscaling and commercialization of this technology. It is well-known that gel electrolytes can improve the long-term stability and allow easy DSSC manufacturing. However, there is limited knowledge on the long-term stability of cobalt-based gel electrolytes and also how this stability is affected when applying different dye sensitizers. Moreover, long-term stability studies have been done with no, or an imperfect, sealing. In this work we investigated the performance and the stability of cobalt-based polymer gel electrolytes using devices properly sealed. Here, two different dyes, an organic and a ruthenium dye, were selected to investigate the device's performance. The cobalt liquid electrolyte was gelled with a PEO-based terpolymer (PEO-EM-AGE) and compared to its liquid counterpart. After 1000 h, the efficiencies of the liquid- and gel-based solar cells with the ruthenium dye were statistically similar to each other. On the other hand, the DSSCs using the organic dye performed similarly by statistical analysis only up to 500 h. Our findings suggest that the choice of the dye has an important impact on the long-term stability of DSSCs and must be considered a key factor in the degradation mechanism.