Top Treating Oils with Additives 

12 Sep 2016

Top Treating Oils with Additives 
Does it deliver optimal equipment performance?

Recently, there has been talk about the potential benefits of top treating wind turbine gearbox oil with additives to mitigate lubricant degradation and extend oil life. But relying on additive top treating as part of a primary lubrication strategy is not a recommended long-term solution to extending lubrication intervals; it may introduce potential complications, something no wind turbine operator wants. 

Instead, the key to long-term lubrication performance is to select an oil that is formulated with the right mix of advanced base oils and additives, and delivers the required performance over many years without the need for additive top treating. 

What is top treating? 
The additive top treat concept seems simple: operators use condition monitoring to identify when an oil’s additives start to deplete and then re-additize that oil with the addition of after-market additive packages. 

While it’s true that all wind turbine oils will eventually start to deplete additives as they work to protect the gearbox, relying on top treating to extend oil life is not a recommended best practice for various reasons, including:

Potential for an unbalanced formulation:  Additive top treating may actually introduce new components, or contaminants, that could impact the performance of a wind turbine equipment by generating an unbalanced formulation. For example, surface active additives like anti-wear additives and rust inhibitors both compete for space on the metal surfaces in a gear box. Formulating an oil so that both of these types of additives are present in the correct amounts (to properly protect the machine elements from both wear and rust) is a delicate balance. Topping up with different ratios or different types of these additives could disturb the balance, creating more potential harm than good.

Increased Safety Concerns: Top treating oils with additives increases with equipment interaction. While top treating may not be as invasive as flushing and replacing an oil, regular additive top treating requires more frequent equipment interaction which, in turn, increases the potential for safety issues.  

Choosing the right oil is better than top treating 
Instead of relying on additive top treating to extend lubricant life, prudent operators should focus on selecting an oil that is formulated with the right mix of advanced base oils and additives to deliver long-lasting performance, without the need for additional additive top treatment.

The best formulated oils will last longer – in some cases years longer – so it will not be necessary to top treat the oil to maintain the expected level of performance. This also results in several key advantages, including less frequent interaction with equipment, and minimized risk of accidentally introducing insoluble contaminants into the lubricants during a top treat service. 

In fact, some of the industry’s top synthetic wind turbine oils are warrantied for up to seven years, demonstrating the capability for the fluid to protect the machine even after 60,000 hours in service.  

The image at left compares various wind turbine gearbox oils. It is evident the high quality oil, formulated with the right mix of base oils and additives, delivers better performance across a wide range of parameters. For key parameters such as oxidative stability, the best formulated lubricant can deliver exceptional performance; it has the potential to better withstand degradation than oils with a less robust formulation. 

That’s why, when it comes to wind turbine equipment, the first, and most important consideration should be lubricant formulation. By selecting the right lubricants, the equipment will be better protected in the long run and it won’t be necessary to take risks with top treating. 

Gary Hennigan is the national accounts executive at ExxonMobil.

ExxonMobil |


Volume: 2016 September/October