Spectro Oils of America Parts & Accessories

Spectro have been formulating motorcycle-specific oils out of Brookfield, Connecticut since 1966. The Golden Spectro line is the one most Harley riders know — a 60-weight that handles the heat in air-cooled Big Twin engines without thinning out and pulling power on a long summer run. Full synthetic, semi-syn, and petroleum options cover engine, primary, and gearbox.

Made for V-twins specifically, not blended for cars and reused for bikes. If you're running an Evo or earlier and want oil that's actually been tested in the application, Spectro is the safe call.