Oven aging was applied for about 8800 hours (more than one year) to evaluate the long-term thermal stability of post-used HDPE material recycled from bottle crates. For recycling, the remelting-restabilization technique was applied. To study the effect of restabilization, crystallinity and melt flow rate were monitored during heat aging. Furthermore, tensile strength and tensile impact strength were followed together with the time until embrittlement. These data were enriched with microphotographs of the specimens' surfaces. Finally, repigmentation was used to evaluate the role of new pigments on the final performance of the recycled material. The results illustrate that restabilization is mandatory for improving the long-term thermal stability of the post-used crate material, enabling its reuse in the original application.