Vintage Sinclair Opaline Motor Oil Porcelain Button Sign

This is a circular, convex 'button' style advertising sign for Sinclair Opaline Motor Oil. The sign features the iconic Sinclair branding, characterized by a vibrant color palette of hunter green, crimson red, and off-white. The central graphic depicts the famous Sinclair Apatosaurus (commonly referred to as a Brontosaurus) in white with green outlines, set against a red circular field. Text elements include 'SINCLAIR' in a custom stylized green font, 'OPALINE MOTOR OIL' in bold white block lettering, and the slogan 'MELLOWED 80 MILLION YEARS' at the bottom edge. Physically, the piece appears to be made of heavy-gauge steel finished with a porcelain enamel coating. It measures approximately 12 to 15 inches in diameter based on visual scale. The condition shows significant signs of age and display; there is a dense network of surface crazing and fine hairline cracks, particularly across the white border and the dinosaur graphic. Noticeable 'flea bites' or small enamel chips are present along the outermost rim, which is typical for authentic porcelain signs of this era. The color saturation remains strong, though there is a slight yellowing or patina to the white sections. This style of signage was predominantly produced during the 1930s to 1950s, representing a peak era for American petroleana and roadside advertising. The lack of a visible maker's mark in the photograph suggests it may be located on the reverse or obscured by the mounting hardware.