Leo Stern and Jacques Sonneborn - innovative oil entrepreneurs and family networkers with a sense of tradition. Merchants Leo Stern and Jacques Sonneborn were key figures in the German oil industry during the Empire: they recognized and actively promoted the growing demand for lubricants. In 1888, they established a factory for mechanical oils, fats, and petroleum jelly in the Hamburg Free Port and developed the Kleine Grasbrook into an innovative site for the refinement and international distribution of novel petroleum products - not without local complaints about increasing environmental pollution. Stern and Sonneborn secured their raw material needs through travels to oil-producing regions in Russia and the USA, as well as through cartel agreements. The reputation of Oelwerke Stern-Sonneborn AG (OSSAG) as a manufacturer of high-quality machine and engine oils for industrial large customers, automobiles, airplanes, and motor ships made them a sought-after supplier for the military during World War I. The Hamburg-based entrepreneurs were active in the city's Jewish community and as donors to the Hamburg Scientific Foundation. The merger of the family business into Rhenania-Ossag Mineralölwerke AG in 1925, which was renamed Deutsche Shell AG in 1947, as well as the fate of both entrepreneurial families during the Nazi era, are traced from private estates, public, and corporate archives into the era of the Federal Republic.