Zinc dialkyldithiophosphate: a multifunctional additive that lays down a protective zinc and iron phosphate tribofilm under rubbing and also breaks down peroxides to slow oxidation. It is the backbone of engine oils and AW hydraulic oils. Phosphorus from ZDDP poisons exhaust catalysts, so passenger car oils cap it, and zinc types can form deposits or hydrolyze in wet systems, which is why zinc-free hydraulic oils exist.
Flat-tappet cam needs the high-zinc oil, the low-ZDDP stuff will wipe the lobes during break-in.
Also heard as
- ZDP
- zinc dithiophosphate
- zinc
Related terms
AW
Antiwear: additives or oils that build protective films to cut wear under moderate boundary contact.
Antioxidant
Additive that slows the chemical aging of oil by intercepting the radicals and peroxides that drive oxidation.
Additive package
Pre-blended mix of performance chemicals that a blender adds to base oil to make a finished lubricant.
Elemental analysis
Spectrometric measurement of wear metals, contaminants and additive elements in oil, in parts per million.