The new and improved Mazda fuel filter is necessary for the fuel injection system on your vehicle. This is a higher standard of cleanliness than what was required for the older carbureted or port injected fuel systems in the past. The reason for an improved performance fuel filter is because it must deliver contaminant-free gasoline to each individual fuel injector. This means that they are spraying extremely clean gas into the combustion chambers. This is as atomized spray that must be at a consistent amount for each cylinder for the Mazda engine to operate at its maximum level. If small particulates are permitted to enter this fuel injector, the amount and level of spray into the combustion chamber will be adversely affected with a clogging of the exit ports. The Mazda fuel filter must now be regularly changed to help keep the entire fuel system clean and in working order. If not, it will have to be torn apart and cleaned. Because of that, it should be placed on the periodical maintenance schedule for replacement at least annually. If your supply of fuel is contaminated, then replacement of the fuel filter should be more frequent. The location of the fuel filter on your Mazda car will vary depending on just which model you have. What is consistent is that it is between the fuel tank and intake port of the fuel injection system. When it is time to replace the fuel filter make sure the car has not been running for at least 5 minutes. The fuel system in your Mazda is pressurized. The 5 minutes waiting will allow for the pressure to decrease to a safe level so when it is disengaged, it will not release a spray of fuel.