Q: What does flushing car fluids mean?

Flushing car fluids generally refers to having a sealed systems fluid completely replaced usually with the use of a machine that is capable of complete fluid exchange. Systems that are generally flushed in our modern vehicles include the coolant system, brakes system automatic transmission, engine, power steering system, fuel injection system, and sometimes even the AC system.

This process is generally done with the use of a machine designed to remove the original fluid in the system, pass fresh fluid or a cleaner through the system and replenish the proper fluid when finished. Flushing can also be done on fuel system lines in the event of a contaminated fuel system. This helps to remove the old fluid which may have lost its lubrication or other properties and removes scale, dirt, and debris, which can affect proper operation and cause further damage. Flushing the system to remove debris would be similar in concept to clearing a partially clogged drain. Using the pressure to force the dirt and old fluids out of the system and replenishing the vital new fluid will help to ensure proper operation and extend service life. For example, coolant over time becomes acidic and corrosive and turns into an electrolyte. Along with losing the lubrication properties which help to keep seals soft and prevent rust and scale, this chemical change can cause actual engine damage to the cylinder walls, head surface, water pump or radiator. In the case of the transmission, the fluid provides the pressure needed to apply the internal clutches for gear selection and lubricates to protect from dirt and wear. Over time, due mostly to heat, these additives will break down and the fluid will lose its ability to protect the internal parts. Flushing restores the fluid and cleans the system. Think of it like a detox cleanse when starting a diet. The key to any vehicle’s long life and lower cost of overall operation is proper maintenance. Flushing should be a vital part of this process.