Should the hydraulic oil be replaced?
August 29, 2018 IN Oil Scrubber
Should the hydraulic oil be replaced?

Should the hydraulic oil be replaced?

This is a common question, which until now had multiple answers, most of which were based on tradition, instead of data.  For example, tradition said to replace the oil if the motor burned up.  The thinking was that the burned out motor left acid the oil and that would cause the next motor to burn out as well.

The reality for most of those cases may have actually been water.  After observing hundreds of oil analysis reports, water is one of the most common chemical contaminates in hydraulic elevators.  It is reasonable to assume that high levels of water could destroy a submersible motor.  It is also reasonable to assume that if water destroyed the first motor, a replacement motor in the same oil would suffer the same fate.  Changing the oil removed the water and the myth of replacing the oil after motor failure endured.

If the hydraulic elevator system only contained ten to twenty gallons of oil, it would be reasonable to dispose of the oil.  However, the hydraulic elevator contains from 150 to over 700 gallons of hydraulic oil, so replacement is not economical.  Fortunately, there is a better alternative.

First, oil analysis should be a part of standard maintenance practice to detect the buildup of water and other developing problems before they cause a failure.  After a failure, forensic analysis of the oil can help determine the cause of failure and determine if the oil should be replaced or if it is suitable for continued use.

In ten years of performing oil analysis on elevators, it is rare that I find oil that is so badly oxidized that it must be replaced.  Typically, the oil is dirty or contaminated, but the base oil is still chemically sound, even if the additive package has been diminished.

Additives are made to be depleted, so a reduction in additives is normal over time.  The purpose of the additives is to improve the base oil and minimize undesirable characteristics of the base oil.  The hydraulic system runs on the base oil; not the additives.  If the oil is clean, cool and dry, many of the additives would not be needed. 

By cleaning the oil and removing the water and oxidation by-products, the hydraulic oil can typically be restored to like new condition; in some cases the oil can test better than new.   The key is the large volume of oil in the entirety of the hydraulic system.

The Oil Scrubber cleans and dries the oil in the reservoir, which then travels through the system dissolving accumulated debris and more importantly picking up unused additives from the pipes and casing.  These retuning additives revive the additive content of the oil throughout the hydraulic system.  Once the hydraulic oil is clean, ten to 15 gallons of top off oil can bring the oil analysis numbers back to like new or better than new numbers; eliminating the need to replace the oil.

Please explore our website, for more information and solutions for restoring the hydraulic oil in elevators.