Aftermarket & OEM Hydraulic Fluid
Dirty hydraulic fluid in any of the system on your vehicle will cause premature aging of the interior components like seals and steel parts. The word dirty can include dirt along with moisture that will cause the hydraulic fluid to discolor and reduce its effectiveness as a means of pushing components to their proper place as they were designed to function. A good example of this is in the braking system where the caliper seals or wheel cylinders would leak and the force being applied to the brake pads or shoes would be reduced because water compresses. Other system affected will be the power steering system and a self adjusting ride height system if one is installed on your vehicle.
The term hydraulic fluid is in reference to specific type of petroleum oil that is used in a closed loop system. Its main favorable characteristic is that it is a fluid that does not compress when pressure is placed on it by an exterior force. Each application of a vehicle that uses a hydraulic fluid is different and they cannot be interchanged. For example the hydraulic fluid used for the automatic transmission cannot be placed in the brake system. The physical result of this action would be the swelling up of the seals in the brake system causing them to fail.
To replace contaminated hydraulic fluid is as simple as draining it out of the system and replacing it with a fresh supply in its reservoir. When changing the hydraulic fluid in the braking system, the nipple in the line on the passenger rear side wheel cylinder is the first one to bleed, then the other rear wheel then the two fronts. This will replace the hydraulic fluid and keep the amount of air being introduced into this closed loop system to a minimum.