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Performance & Hotrod Business - December '14

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December 2014 n Performance & Hotrod Business n 69 there is no protective, anti-wear barrier film on these surfaces. Introducing Zinc Since the 1920s, either zinc diathyldi- thiophosphate (ZDDP) or zinc dithiophos- phate (ZDP) has been the primary source of this barrier film. This is the "zinc" everybody talks about. It is not the metal element zinc as used to galvanize metal but is the name of a group of chemical compounds. The basic molecule of these compounds is polar, meaning that like a magnet, they are attracted to iron and steel. These are a chemical soap when used in oil. They quickly attach themselves to the engine metals but offer little (or no) protection to the metals until they are subjected to heat and pressure, causing them to form a glass phosphate coating—the desired anti- wear boundary film. There are about 50 different ZDDPs. Each has a chemical formula designed for a specific purpose. One ZDDP may be known as a "fast- burn zinc." It easily penetrates new raw metal and quickly forms a protective coat- ing—but it is not durable. These type of ZDDPs are used to quickly break in new engines, minimizing the friction and wear at start-up. Since they do not last, break-in zincs must be replaced in a few hundred miles with an oil that has a harder, "slow- burn zinc" for durability. This zinc is too hard to use as a break-in additive. That is why most oil cannot be used successfully for break-in. To add to the confusion, these zincs are not usually compatible. Some ZDDPs mix well with some of the others. Some do not. Trying to put two different zincs together is chemical rou- lette. Sometimes there is success. Sometimes you lose camshaft lobes. This is one reason ZDDP additives are risky at best and, unless you are a chemist with an understanding of oil mol- ecule components, you may not have success with mixing two different zincs. When choosing an oil for your old car, choose one that has the right formula for an old car. Specifications established by the American Petroleum Institute for current cars and trucks don't meet the requirements for engines built before 1995 that have flat tappets. Remember: there are about 50 varia- tions. None are right for every applica- tion. Each one is designed for a specific application. Detergents Also needed in oil is a group of chemi- cals used as detergents. Like zincs, these detergents are composed of polar mole- cules. Their job is to adhere to the metals to protect them from dirt. Unfortunately, detergents don't know zinc from dirt. In a new engine, some of the detergents get to the metal first and win the "detergent versus zinc" battle. When this happens, camshaft lobes fail. Again like zinc, there are many formulas for these detergents and, you guessed it, all are not compatible with each other or with all the different ZDDPs. In today's selection of oils, only "break-in oil" is suitable for starting a fresh engine. Some brands are better than others, but all break-in oils are better than any available motor oil. With a good break-in oil, no additives are needed. The "good old days" of using 30W non-detergent oil for break-in are history because it is obsolete as a motor oil. It is still used for compressors, conveyor bearings, small engines, etc., but no longer formulated for engines. It does not have the modern anti-wear or anti-corrosion ingredients needed. The amount of ZDDP and the amounts of detergent in the engine are critical. There must be a proper balance for each

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