You guys that are adding zinc to your oil are just throwing money away. First, with all the specialty oils on the market today, if you're using an oil that you think you need to add something to, you're using the wrong oil. Second, adding zinc to oil is like adding sugar to iced tea. Anyone from the south knows that when you make sweet tea, you add the sugar to the tea when it's hot while you're making it. Same with zinc. It needs to be added to the oil when its blended at the refinery during the high temp and pressures of the process. Zinc does not blend with your oil in the oil pan and just goes out with the next oil change...not to mention that there are about a dozen or more types of zinc. Third, the oil manufacturers spend a lot of time and money coming up with the precise blends of zinc, detergent, calcium and other ingredients in your oil and unless you're a chemist or tribologist, more times than not, you could be doing more harm than good. Break in oils are specially formulated for exactly that; break in and they are not all the same. I've been watching/listening/learning from Lake Speed Jr for years as he helped develop the Joe Gibbs, now Driven line of oil products. Lake is a wealth of knowledge and a very open book to his testing and results. I wouldn't use anything but their break in oil and their Hot Rod line is specifically formulated for older "hot rods" with flat tappet cams. Their new GP1 oil is based on a true Pennsylvania crude base and has been tested and proven to be one of the best oils on the market.