 This paper investigated the rheological properties of a lubricant used in bridge structures. It developed a methodology to measure the viscosity of the lubricant using a rotational viscometer. Additionally, it identified the mathematical model of the lubricant's behavior by applying two different approaches, the Onand model and the Prony series. These models can be used to numerically predict the structure's performance over time, allowing for better understanding of the lubricant's behavior and its impact on the structure's longevity. This article was authored by Yuri Onosov and Anna A. Kamenskic.