At a fleet maintenance center we created some labels that identified a product called Oilmax. It listed some info and we pasted them on bottles. We filled the bottles with Motorcraft 5w-20 engine oil and pink dye used for chasing leaks that also has a strong aroma. We picked ten drivers that take really good care of their company cars and are known for their knowledge of maintenance among the mechanics and management staff. They were briefed on the new Oilmax additive that improves mileage and protect you engine like no engine oil alone can do. They were told it was not a CP and that it had a special boron attitive complex and gave them enough info for them to google behind our backs. They would told to fill the gas tank from the same exact pump for 2k miles and keep accurate records including driving conditions experienced, calculations at the pumb and info feed back from on-board readouts. Oilmax turned out to be everything claimed on the label. The lowest increase in mileage was 2% and the best was 5.2%. We were busted by one driver that did a voa on the additive and we were able to shut him up before he ratted us out. that we got. This test was not science but we did it because lots of drivers come to us with requests to use this or that additive and I did not want to alway appear like the grinch. Our test proves that it is difficult to evaluate additives without a broad base of experience and lab work with careful evaluation. I do believe that these drivers were honest and careful and that they got exactly the numbers that they reported. I don't think that Oilmax and the engine was not the cause. It was Oilmax and the driver.