Lubricant Additive Effects on Cam and Tappet Wear in Medium Speed Diesel Engines

For over thirty years zinc dithiophosphate (ZDP) has been used successfully as an oxidation inhibitor and anti-scuff/ anti-wear additive in automotive lubricants primarily to protect cams and tappets in gasoline engines. However a number of researchers have recently reported accelerated wear of cams and tappets in automotive diesels, attributed to diesel soot disabling the ZDP in some manner. This raises questions as to the need for ZDP in large bore medium speed diesel engines. To answer this question an extensive review of the literature was conducted.