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Can Additives Be Replenished?

“What happens to the additives in oil over time and is there any way to replenish them?”

Over time, additives are depleted performing the function for which they were intended, degraded by hydrolysis, mechanical shearing, condensation settling, water washing, particle scrubbing, etc.

The rate of depletion or degradation depends upon the application and the environment. In particular, heat, pressure, shear rate, fuel sulfur, soot, dirt, water, aeration and the presence of catalytic metals (copper, iron, etc.) affect the rate of depletion.

Regarding replenishment, whenever you top-up a system, you are replenishing additives. Likewise, you can perform a partial drain and replacement (often referred to as bleed-and-feed).

A bleed-and-feed strategy can work if the base oil is not degraded. If the base oil has been degraded, adding new oil is analogous to sending a healthy person into a room full of sick people with the hope that his or her good health will be contagious. The additives in the new oil might be compromised within the first hours of use, leaving you right back where you started.

Casual addition of additives into a formulated oil can be dangerous and should be avoided. When in doubt, consult your lubricant supplier.

This article is taken from http://www.machinerylubrication.com/Read/28591/additives-be-replenished

The Basics of Synthetic Oil Technology

In the 1930s, Dr. Hermann Zorn of Germany was searching for a lubricant with the properties of natural oils derived from crude oil but without the undesirable properties (high pour points, tendency to gum or gel in combustion engines, low oxidation resistance at higher temperatures, etc.). Germany was also in need of a product that was not derived from crude oil, as the nation’s access to crude oil was becoming increasingly scarce. By the mid-1940s, the fruit of Dr. Zorn’s labor included more than 3,500 different blends of esters, including diesters and polyolesters.

The first real-world trial for these lubricants came during World War II when both Germany and U.S. forces began using synthetic base oil in aircraft engines. They noticed the synthetics made engine starts much easier in colder climates (due to the high viscosity index) and significantly decreased soot deposits that would build up in oil radiators when using conventional (crude oil-derived) lubricants.

Types and Terminology

There are two American Petroleum Institute (API) base oil categories that include synthetics. The first is API Group IV. The only synthetic base oil included in this group is polyalphaolefin or PAO. PAOs are made by polymerizing an alpha-olefin molecule like ethylene. In an alpha-olefin molecule, there is a carbon-carbon double bond with hydrogen branching off.

The second category is API Group V. These are non- PAO synthetic bases. Examples include diesters, polyolesters, alkylated benzenes, phosphate esters, etc. Basically, if it is a synthetic and it is not a PAO, it is a Group V.

Some confusion has arisen recently regarding the use of the word “synthetic.” Several petrochemical companies have developed processes involving catalytic conversion of crude oil base stock under high pressures and temperatures in the presence of hydrogen to form very high-quality mineral lubricants. These oils, which are known as API Group III, are so highly refined that their properties almost match that of the Group IV synthetics. They are so close in fact that the U.S. court system sided with a manufacturer of these Group III “synthetics” when a lawsuit was brought up for false advertising. Even though these Group III base oils are derived from crude oil, they can now legally, from a marketing standpoint, call them synthetic.

When to Choose a Synthetic

When designing a lubrication program, I use a very simple set of rules to know when to choose a synthetic for an application. They are as follows:

when equipment-performance demands exceed the capabilities of mineral-based fluid,
when synthetic properties can become problem-solvers,
when life-cycle cost savings can be realized, or
when safety and environmental issues can be enhanced.

This article is taken from http://www.machinerylubrication.com/Read/28671/basics-of-syntic-oil-technology-

When is It Hot Enough for a Synthetic?

“My supplier is pushing hard to move his synthetic gear oils into my operation. His position is that the units run too hot for long-term use of mineral oils. At what temperature should I switch to a synthetic lubricant for a non-circulated gearbox?”

First, the term synthetic is very broad, so we assume you are referring to lubricants that are formulated using polyalphaolefin (PAO) synthetic base oil.

There is no single temperature point that dictates a time to move to synthetics. The decision is dependent on equipment continuous loads and shock loads, equipment availability for routine maintenance, criticality of the application, component life cycles, lubricant life cycles and failure modes among other things.

Generally, the rate of lubricant degradation doubles with every 18 degrees F increase in temperature. Once formulated with antioxidant additives, PAO-based lubricants have a lower baseline rate of oxidative degradation. At low temperatures, a PAO’s increased oxidative life may not be noticeable, particularly if you have to change the oil at some point for other reasons. At higher temperatures, the synthetic may last noticeably longer.

Typically, you begin to notice the extra life provided by a PAO above 160 degrees F. If it is above 180 degrees F, and especially 200 degrees F, the difference in oxidative life becomes quite apparent. However, the point at which a change to synthetic is justified is dependent perhaps on a handful of additional “program management” parameters such as:

1. Do you intend to run your gear oils with an appropriate use of filtration and oil analysis to support life-cycle extensions for many years?

2. Are you currently doing oil analysis and performing condition-based changes?

3. Do you have, and have you communicated to your lab, oxidation limits that flag impending oxidation problems?

4. Does the machine’s operating temperature vary a great deal (a PAO’s high viscosity index enables it to operate across a wider temperature range)?

5. Do you have an effective contamination control program in place that will enable you to fully exploit the PAO’s extended life?

With the appropriate management strategy, a change to a high-performance product can actually cost considerably less than the equivalent mineral oil product type. Outside of these considerations, somewhere around 165 degrees F represents the point at which you probably should begin to consider the use of synthetics for the sake of lubricant longevity, if not for the sake of reliability.

This article is taken from http://www.machinerylubrication.com/Read/28606/hot-for-synthetic

Lubrication Myth

This video explains why relubing once a year is not enough and that relubrication is necessary to replenish grease in bearings when the current grease breaks down or deteriorates. Learn how pumping new grease into a bearing helps to flush away contamination while the old grease is pushed out, as well as how relubrication intervals can vary based on load, speed, temperature or environmental conditions.

This article is taken from http://www.machinerylubrication.com/View/29055/relubing-lubrication-myth