If your project vehicle is pre-1989, ZDDP Oil Additive is a must for keeping that engine running smoothly. Today's motor oils won't provide the ZDDP your older engine needs, unless you add this ZDDP Oil Additive!
After 70+ years, the EPA mandated that all domestic motor oil producers remove ZDDP (Zinc Dialkyl Dithio Phosphate) from all conventional and synthetic motor oils. If your engine was designed before 1989, the non-roller lifters still require ZDDP to avoid premature deterioration.
ZDDP alters bearing and journal surface characteristics to prevent metal-on-metal contact. ZDDP also reduces the tendency of parts to scuff or gall under heavy loads.
*Add a 4 ounce bottle of ZDDP to every 4 or 5 quart oil change.