Canada Moto Guide: HomeMotosGearTouringEvents

Yet another oil thread

Zinc dialkyldithiophosphates (often referred to as ZDDP) are a family of coordination compounds developed in the 1940s that feature zinc bound to the anion of dithiophosphoric acid. These uncharged compounds are not salts. They are soluble in nonpolar solvents, and the longer chain derivatives easily dissolve in mineral and synthetic oils used as lubricants.

The main use of ZDDP is in anti-wear additives to lubricants such as greases, gear oils, and motor oils, which usually contain from 600ppm for some modern energy conserving low viscosity oils to 2000ppm of this additive in some racing oils. It has been reported that zinc and phosphorus emissions may damage catalytic converters and standard formulations of lubricating oils for gasoline engines now have reduced amounts of the additive due to the API limiting the concentration of this additive in new API SM and SN oils.

Crankcase oils with reduced ZDDP have been cited as causing damage to, or failure of camshafts and lifters which undergo very high boundary layer pressures and/or shear forces at their contact faces, and in other regions such as big-end/main bearings, and piston rings and pins.

SO - as well as doing damage to wet clutches, oils with friction modifier additives and lower ZDDP levels can also roast a lot of expensive moving parts.

Note to Rotella fans - light viscosity diesel oils have also lowered ZDDP amounts to reduce particulate emissions - take your chances.