Why does oil contain ZDDP (zinc)?

In simple terms it builds a sacrificial layer that projects components form metal to metal contact.
It is a polar molecule that bonds to surfaces and provides a protective layer. This is particularly important in areas of high load, where the oil is effectively squeezed out under load and the only thing providing protection is the layer of zinc.

So why is it important to understand what ZDDP do. Well the issue is that as you read this you probably own a high performance, classic or racing vehicle or a combination of those. Modern oils are, due to environmental standards, low in ZDDP and high in detergents to sustain up to 18,000 miles service intervals. This works fine for modern cars driven at low percentage of their maximum performance between A and B, sitting in traffic etc. However, older types of engines, tuned engines or engines that are driven at 100% (racing) need more ZDDP to reduce internal engine wear that otherwise occur with newer standard oils. Driven Racing Oil’s range of XP, HR and Street Performance oils are loaded with ZDDP to protect your engine – take our word for it, you need an oil that is designed for your engine – not to meet API or ACEA environmental standards.