The Advantages Of Lubricants Formulated With True Synthetic Group IV and Group V Base Stocks

by MPT Industries

We often stress the importance and advantages of true synthetic base stocks over mineral oils that are classified as Group III synthetics (hydrocracked, highly refined base stocks). So what exactly are the advantages? We explore them below:

Group IV

Within the industry, base stocks that are formulated with mineral oils are classified as Groups I and II. Those mineral oils that are hydrocracked and highly refined are classified as Group III and are commonly marketed as synthetics. Group IV base stocks represent the entry level into the true synthetic base oil market. These base stocks are known as polyalphaolefins (PAOs). They are the most common base stocks found in true synthetic lubricants because of their relatively low cost. They are also known as synthetic hydrocarbons because their structure resembles that of a hydrocarbon or mineral oil.

Polyalphaolefins are uniform in structure with no inconsistencies in the size of each molecule. Unlike mineral oils, they do not contain wax or any foreign matter. Some of their impressive characteristics are listed below:

  1. High Viscosity Index -- Less change in viscosity as application temperature increases.

  2. Better Pour Point -- Flow better in cold temperatures than mineral based oils.

  3. Less Volatility -- Lower volatility means less evaporation loss which is exhibited by less need to add more lubricant during high temperature operation.

  4. Thermal Oxidation Stability -- Resistant to breakdown.

Since PAOs are not very soluble, they are often blended with Group V ester base stocks which have better solubility and the ability to counteract seal shrinkage issues.

Esters are the most popular form of Group V base stocks. They are formed by condensing an acid with an alcohol and have these impressive characteristics:

  1. As with PAOs, esters provide a high viscosity index and low pour point.

  2. Non-toxic, biodegradable and environmentally friendly.

  3. Excellent solubility -- Provide ability to help properly blend additives into formulation.

  4. Thermal Oxidation Stability -- Excellent protection during high temperature operation.

In summary, most will agree, true synthetic base stocks when combined with the proper additives that are appropriate for a given application, will provide superior performance characteristics over mineral based oils. However, they are also more expensive. As a result, you will need to do your own personal cost versus benefit analysis.