The compositional changes a diesel fuel undergoes during hydrotreating were investigated, specifically in relation to the changes in natural lubricity components. A unique set of six diesel fuels from the United States, England, Israel, and Spain were hydrotreated to four different levels of sulfur and aromatic content. Three different ASTM methods were used to determine the lubricity of these samples. These tests showed that the lubricity of the fuels was severely impacted by the hydrotreating process. A chemical test was developed that employed a base extraction followed by GC analysis that positively correlated with the ASTM tests. Additionally, GC/MS was employed to determine the major classes of compounds that are responsible for a fuel's inherent lubricity. The samples were aged at ambient conditions for two years as well as undergoing accelerated aging experiments. There appears to be a fuel dependent relationship between aging and compositional changes that affords a fuel its lubricity.