AMSOIL Z-RODâ„¢ Synthetic Motor Oil is specially engineered for classic and high-performance vehicles.
It features a high-zinc formulation to prevent wear on flat-tappet camshafts and other critical engine components,
along with a proprietary blend of rust and corrosion inhibitors for added protection during long-term storage.
Here's the 'rest of the story' with technical information so you can compare it to the 'competition'
10W-30
http://www.amsoil.com/storefront/zrt.aspx
20W-50
http://www.amsoil.com/storefront/zrf.aspx