I've noticed a lot of diesel owners could use some info on how to use their Filter Minder. The Minder is just a messenger, and is only telling the vacuum level on the clean side of the air filter. Depending on how it was engineered with the air induction system, with a new filter it may show zero, or may be up a notch or two. This is the clean filter restriction level. The typical air filter takes a long time to show any additional restriction from dirt/dust. It may take 50-75,000 miles depending on operating conditions. If you pull a filter and look at it, it will look dirty...........that's it's job !!!! In fact, it filters better than a new filter if it has a dust film. If you don't see the Minder go up, there is no increased restriction. If you change to a different aftermarket filter and see a difference in the Minder reading...........it's just telling you if that filter is more or less restrictive. If it goes all the way to red zone, you may want to think about what type of filter you just installed, as you've just increased the restriction in your air induction system. We've been taught for so many years that we need to constantly change air filters, and that's just not true. Many air filters will last 100,000 miles or more. If you just like changing filters frequently, that's fine, but don't blame the Minder. For more information go to www.filterminder.com