Understanding and Managing Oil Leaks

Bennett Fitch, Noria Corporation
Tags: lubrication programs

A cartoon-like illustration of some sort of industrial machine. The machine is orange. At the base of the machine is a puddle of yellow oil. This same oil is also seeping from the side of the machine. A large bandage is on the machine, covering the spot from which oil is leaking.

We all know leaks make a mess. Why do they keep happening? How do we know if a leak is something to be concerned about or if it is just commonplace for plant equipment? Well, given that rotating equipment and lubricated equipment are practically synonymous, oil leaks can be more common than we would like. Thus, understanding the risks associated with an oil leak is important. While preventing leaks all together is desirable, it’s often not achievable. Therefore, we must be ready to reduce the leaks to an allowable amount based on variables of risk. For now, we’ll focus on oil leaks, although much of what will be mentioned could also apply to grease leaks.

Any time oil escapes the lubrication system (sump, piping, etc.) and enters the external surroundings, this is an external leak. We are often aware of this, as there is visual evidence of the oil dripping out onto other components and forming a puddle on the floor. However, another type of leak occurs when unwanted oil seeps between internal chambers inside a lubrication system. This is called an internal leak. Not many consider internal leaks at all, much less the risks associated with them. This is largely because of the lack of evidence. Unless we are monitoring pressure gauges or operational movements closely, these internal leaks may go unnoticed.

But regardless of the type of leak, what is considered normal? Is there any amount of leakage that is allowable? When should a leak be taken seriously and corrected? Is this a maintenance activity that is largely reactive or can steps to be taken to be more proactive?

Image of a dirty machine and a stack of dirty barrels.

Leaks are something I often inspect for and help identify through Noria’s Lubrication Program Development (LPD). During the first phase of LPD, an assessment is performed and aligned to the 40 Factors of the Ascend™ methodology. One of these factors is Leakage Management (E3M). After a plant undergoes an Ascend Assessment, there is often the need to bring awareness to the abnormal state of leaks that exist. The reality of what is considered “normal” is not what should be allowable. Most leaks are manageable, and if not, the result can be excessive costs, or worse, a hazardous work environment.

The Cause of Leaks

It’s easy to blame a machine that is considered “a leaker” on some error in manufacturing or on actions taken during a rebuild. Sometimes this may be true. If there is not enough attention given to the type of material used or to component assembly, then any hope of controlling leaks may be doomed from the start.

Other times, a leak is blamed on a symptom rather than root causes, like when housing corrosion or worn seals produce a leak. While these symptoms may be the source of the leak, they only failed because of something else: the root of the problem. If you’re going to have any chance of preventing a leak from recurring, the root cause must be uncovered. Targeting the root cause helps make the most of the reactive nature of a leak fix by creating a more proactive and sustainable solution. In most cases, the root cause of a leak stems from either a selection decision, negligence with maintenance or improper operations.

The Effect of Leaks and Overall Risk Concerns

Some leaks start small and stay small. In a perfect scenario, this would give maintenance ample time to discover the leak during routine inspections and follow up with corrective action. Other times, leaks are more significant and it’s critical to act quickly. Don’t be fooled by the size of the leak, as this doesn’t always identify the level of risk or urgency of action. In fact, small leakers are often the biggest risk, simply because they are more likely to go unnoticed or without much concern afforded to them.

Take for example a leak with a rate of about one drop per second; it would take less than a day for a gallon of oil to leak out. That means a typical process pump would be out of oil during a single eight-hour shift. For a large oil reservoir, this could add up to more than 400 gallons of oil lost over the course of a year.

First and foremost, any leak that is not adequately contained can present dangers to the environment. Most of us are familiar with the severity of larger leaks of hazardous oils into waters or other areas with wildlife, as well as the high cost to the responsible organization in the form of fines and any environmental cleanup efforts.

Leaks can also pose a risk to our health in many ways. They can create a potential fire hazard or slip and fall opportunities. Even more dangerous is the risk of the leak finding its way into product that will eventually be consumed. While this is of more concern at food processing facilities, this type of risk can occur at any plant, especially those around waterways.

As it relates to the equipment, a leak can certainly lead to lubricant starvation issues and reduced machine performance. In the example of the process pump, it wouldn’t take much oil loss to result in a lubrication issue, ultimately leading to machine failure. Larger systems such as hydraulic systems are more prone to leaks with actuators or other high-pressure areas. While some minimal amount of oil loss in these types of machines may be considered “allowable,” it can still lead to reduced efficiencies, loss of control and an overall reduction in equipment reliability. These equipment effects may seem subtle and insignificant, so the cost impact often becomes evident after it’s too late to avoid. Such is the case if these equipment inefficiencies lead to product damage or other deficiencies in production results.

There are many other risks that can result in both external and internal leaks. Sometimes the effects are just one link in a chain reaction of cause and effect, which can eventually lead to equipment failure. Contamination ingression, for example, which can enter at “leak point,” may very well lead to a failure. This leak point could either be in the headspace or a chamber under vacuum pressure.

While the cost of the oil was briefly mentioned as a risk above, it often pales in comparison to other substantial risks presented by leaks such as the cost of labor required to handle them.

Close up of a machine part with grease

5 Steps to Managing the Leaks


If you work at a facility where oil leaks are commonplace, then it may be time to devote the effort needed to accomplish proper leak management. Once they are justified by the identified risks, the practical steps can be approached for each individual occurrence. Although precise and frequent inspection practices are a must for identifying leaks, don’t ignore their significance once they are found. The risks can be greater than just a financial concern. Ultimately, when leaks are minimized equipment will become more reliable and working in a cleaner workplace can allow for more necessary improvements in the plant to take place.


Fitch, E. C. (1992). Proactive maintenance for mechanical systems. Oxford, England: Elsevier Advanced Technology.