Is there a defined temperature at which synthetic gear oil is clearly better than crude.

We’ve all been told that synthetic gear oil is unsurpassed when operating at high temperatures: But what are the “high temperatures” at which point they’re clearly superior to mineral based products.

There are many classes of synthetic gear oil.

The term synthetic is very broad, so we’ll refer to lubricant that is formulated using polyalphaolefin (PAO) synthetic base oil – also known as fully synthetic lubricant.

When should I use fully synthetic gear oil?

There is no single temperature point that dictates a time to move to synthetics. There are many factors you need to take into consideration, which all contribute to the decision.

• Equipment continuous loads. 
• Shock loads. 
• Routine maintenance intervals. 
• Criticality of the application. 
• Component life cycle. 
• Lubricant life cycles. 
• Failure modes. 

Generally, the rate of synthetic gear oil degradation doubles with every 8 degrees Celsius increase in temperature.

Thus if the synthetic gear oil is formulated with antioxidant additives, PAO-based lubricants have a lower baseline rate of oxidative degradation. So 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: But at higher temperatures, synthetic gear oil should last noticeably longer.

Typically, you would begin to notice the extended gear lubrication life, provided by a PAO, above about 70 degrees Celsius. If it is above 80 degrees C, and especially 90 degrees C, the difference in oxidative life becomes quite noticeable.



However, the point at which a change to synthetic gear oil is justified is dependent perhaps on a handful of additional "program management" parameters such as:

• Is there an appropriate use of filtration and oil analysis to support life-cycle extensions for many years?
• Are there set oxidation limits that flag impending oxidation problems? 
• 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)? 
• Is there an effective contamination control program in place that will enable you to fully exploit the PAO's extended life? As opposed to filtration this refers to environmental contamination by things such as water. 

If best industry practices are in place, a change to a high-performance synthetic gear oil can actually cost considerably less than the equivalent mineral oil product type – irrespective of operating temperature.

But to give a short answer: Outside of these considerations, anything over 75 degrees C would represent the point at which a synthetic gear oil should be considered: At least for the sake of lubricant longevity, if not for the sake of reliability.

There are many types of synthetic gear lubricants available, but at Habot Synthetic Lubricants, we have the range and experience to offer you the best synthetic gear oil for your requirements.