Both gasoline and Diesel fuel injectors play a very important role in a vehicle's performance. They must spray a very precise amount of fuel in a very precise spray pattern at a very precise time. They must perform this task every time each cylinder fires. This relates to about 90,000 times every mile. They must perform their task in some very harsh environments. The inside of a cylinder can get to about 1700 degrees. Gasoline and diesel fuels tend to leave a deposit behind wherever they have been. Deposits left in the very small passages inside an injector can build up. This affects the volume of fuel passed as well as the ability to SHUT OFF between times it injects. Gasoline and diesel fuel vapors that are left over after an engine has stopped running will evaporate and leave behind another deposit. It builds up inside the air intake system and on the outside of an injector tip. This affects the injector spray pattern. Gasoline and diesel fuel injectors stand up to the task quite well. However after time their performance can deteriorate slowly enough for a driver to not even know it. The higher quality of the fuel that is run in a vehicle the longer it can perform well without injector maintenance. Flushing the injectors can clean out deposits and restore the injectors to perform as they were designed. However if an injector is run too long with deposit build up, even a flush job may not always help. For these reasons we recommend gasoline and diesel injectors be flushed after the vehicle has been operated between 60,000 and 100,000 miles or any time we suspect build up may be affecting their performance.