10w40 oil with zinc

Modern conventional oils no longer contain the levels of zinc – and particularly ZDDP – that were found in many older cars. This reduction has been the result of changes in the American Petroleum Institute’s (API) lubricant ratings since 1994. The lack of zinc means that some older engines experience a short period of time where critical metal-to-metal lubrication is not occurring between camshafts and cylinder walls. This is especially evident in a lot of older muscle, classic, and hot rods with flat-tappet camshafts.

Zinc dialkyldithiophosphate, commonly called ZDDP, is an anti-wear additive that works to create a boundary layer inside your engine. This layer sticks to your metal surfaces, minimizing friction. It also minimizes corrosion by preventing oxidation of the metals, and it slows the rate of heat transfer to your internal parts.

The higher zinc levels in this product help your engine get the lubrication it needs, even under high load conditions. The higher molybdenum and phosphorus levels also improve the film strength between your piston rings and cylinder wall, improving seals and protecting against damage from low pressure.

This AMSOIL product combines a premium synthetic base oil with an advanced additive package to provide superior protection and performance. It is ideal for high-mileage vehicles, and provides extra anti-wear protection for old pushrod and flat-tappet camshafts. It also includes storage protection additives to guard against rust during extended winter storage.