I shot the folks at Amsoil a note and asked which oil they'd suggest for an Airhead BMW and a Savage. Asked about ZDDP content in their oils.
Here is the response:
Good evening Armen – thank you for your email and interest in AMSOIL. AMSOIL provides synthetic lubricants and filtration products unequaled in the world.
Zinc Dialkyl Dithiophosphate (ZDDP) is an anti-wear additive used in many different types of lubricants. New additive technology has reduced the importance of ZDDP, although it is still effective.
All of the AMSOIL Synthetic Motorcycle Oils have ZDDP and other additive technology that are used with base fluids that have excellent additive compatibility. As a result, AMSOIL Synthetic Motorcycle Oils protect against wear better than other motorcycle oils, regardless if these other oils have ZDDP or not. Just having ZDDP or any other anti-wear additive in a lubricant doesn’t mean a whole lot if it isn’t effective. The formulation has to have additive compatibility, which is a synergy that occurs giving the additives a stronger benefit than what would otherwise occur.
AMSOIL has several viscosities in the high performance motorcycle line, including 10W30, 10W40, 20W50, and 60. They are included in the Metric, Dirt Bike and V-Twin applications. Some of the older BMW’s used 10W40; most of the newer models use 20W50. Most Suzuki’s use the Metric 10W40 formulation.
You can check out most of them here:
http://www.thebestoil.com/applications/amsoil-synthetic-oils-and-filters-for-... Bottom line, use the appropriate viscosity for whatever motorcycle you are working on. They all have the same anti-wear protection and full benefit package.