In 1938, Leonard began selling products to consumers under its own name. Leonard became a major regional gasoline company marketing its products primarily in Michigan’s Lower Peninsula but outside of metropolitan Detroit. By 1961 more than 700 service stations were either directly owned by the company or were independently operated and selling gasoline under the Leonard brand name.

Most of its early advertising campaigns focused around the quality of its product and the services offered at the many gas stations which sold Leonard gasoline. In the 1950s Leonard focused many of its promotions on selling very high octane fuel to motorists. In 1953 Leonard was the first company in the country to offer 96 octane gas to the public. In 1957 the company upped the octane race by offering 105 octane fuel; a rating sufficient for most small aircraft and any automobile sporting aviation-like tail fins.

The firm, however, realized in the mid-1950s that while high octane gasoline and the advertising around it had won the company some success, it was not very distinctive. Sinclair, for example, was selling its own high octane gasoline, “Power-X,” which it claimed was “power-primed with rocket-fuel.” Consumers found it difficult to distinguish Leonard’s advertisements from those made by the company’s competitors, which also claimed to sell quality gasoline and offer superior service.