Industrial gear oil PAG-PAO

First of all, industrial gear oil is a category comprises 2 different types of base oil which differs in terms of chemical viewpoint:

Mineral types of industrial gear oil and Synthetics


Among industrial products of Mehrtash sepahan Co., the mineral type and synthetic type is available.

All these types are available in domestic and global market under SUNOL product brand as Industrial gear oil.

These products are ready for export and has been reached Far East several years ago, achieving an outstanding rate of customer satisfaction

There are 3 main categories for synthetic industrial gear oil named SUNOL-S and SUNOL-PG, based on these base oils: PAO (polyalphaolefins), PAG (polyalkyleneglycol) and Ester oils (E).

How much do you know about synthetic industrial gear oil?


Most noteworthy, if mineral industrial gear oils are not proper in industrial applications due to their chemical restrictions, therefore synthetic gear oils are proper choices.

Here are some vital features which proves that synthetic gear oil is a suitable option:

  • Extremely low or high temperatures
  • Very high loads
  • Highly important requirements such as flammability
  • Very specific ambient conditions

Limitations of Minerals


There are limitations for improvement of additives for mineral industrial gear oils, because of their chemical structure and formulation, hence still there are some physical properties which cannot be affected in a special way:

  • Thermal resistance
  • Evaporation losses
  • Fluidity, pour point , related to low temperatures
  • Flash point

Considerable benefits


Even though some synthetic industrial gear oils show enhanced performance in relation to mineral types, but still there might be some situations in which minerals are better.

Moreover, possible benefits of synthetic types of industrial gear oil such as SUNOL-PG are as follows:

  • Improved properties related to low temperature
  • Enhanced thermal and oxidation resistance
  • Better viscosity-temperature behavior, high viscosity index
  • Evaporation losses in lower amounts
  • Reduced flammability (in some situations)

Some disadvantages


In addition to the benefits of synthetic industrial gear oil, there are still several drawbacks including:

Material compatibility issues (elastomers and etc.)
Limited compatibility with mineral oils

Similarly, under severe loads and operating conditions, synthetic industrial lubricants are still the best option and benefits are more than disadvantages of such type of industrial oils. As a result of such phenomenon there are spreading use of synthetic industrial oils.

Industrial lubricants based on PAG & PAO


Low friction coefficients are ensured by synthetic lubricants. Such capabilities make them proper choice for hypoid and worm gears. In reliance on proper additives anti-wear protection is another benefit for situations with bronze and steel worm gears. Also EP performance is available by these synthetic industrial gear oils.

Polyglycols with higher polarity in gear systems, provide enhanced touch on metal gear surface. Bear in mind that even without additives, polyglycols provide EP performance. In real performance of SUNOL-PG and SUNOL-S technicians can see such improvements.

Such industrial gear oils (PAG) are not fully compatible with sealing and some paints may dissolve in these base oils. In temperatures above 100°C, fluorinated and PTFE seals are compatible. We do advise engineers to check the compatibility of paints, seals and so on in system prior to utilized PAG.

There are several restrictions in miscibility with mineral oil types. Hence, the latter type obviously should not mix with synthetics. Ferrous and non-ferrous metals are neutral to PG industrial gear oils.

In sliding movement and severe load conditions, in presence of aluminum or aluminum alloys, some increase wear might occur.

Improved oil change intervals based on synthetic oils


Aging and high temperature resistance in synthetic oil are normally seen by technicians. Also improved service life in relation to mineral oils are achieved. 3 to 5 times longer drain intervals are achieved by synthetic base oils including PAG and PAO. Gear oil change intervals in 80°C (176°C) are:

  • 5,000 operation hours in mineral case
  • 15,000 operation hours in PAO case
  • 25,000 operation hours in PAG case (PAG gear oil, sunol-PG)

Friction coefficient are lower in synthetic oils in relation to mineral ones. Also improved relationship of viscosity-temperature are of other impact of synthetic gear oils brought by these oils for gearbox.

Based on these characteristics possibility of using synthetic oils in lower viscosity grades and reduced temperature of oils escalates. Life extension factor in these cases related to oil change interval are longer than numbers mentioned previously in identical oil temperature.

machinery lubrication experts in a splash lubricated worm gear test rig tested three lubricants . You may see such advantage by these numbers.

After 300 operating hours in following oil sump temperatures, here are some records:

Mineral oil: 110°C (230°F)
PAO: 90°C (194°F)
PAG: 75°C (167°F)

The life extension factors of synthetic industrial oils as compared to mineral types are mentioned here:

Mineral oil: 1
PAO: 9.5 times longer
PAG: 31 times longer

Saving repair, maintenance and disposal costs by synthetic oils


In relation to mineral oil types, intervals for oil change of synthetic oil types can be even five times longer under the similar thermal conditions. In spite of the fact the commodity price and the expenses of disposal of synthetics are much higher than that of a mineral oil, the enhanced oil change intervals might offset these expenses when the gear unit’s extended service life are considered.

Moreover, a comparison of the expenses for mineral and synthetic oils gives us real opportunity. Meaning that optimized maintenance cost and enhance reliability of machine were achieved. Similarly, there is also the benefit of reduced environmental effects with lower disposal rates of lubricant.
Selection of oil’s viscosity
As it is mentioned previously, there is a vital parameter in selection of right gear oil named viscosity.

In most situations, manufacturer of gearboxes mention some authorized viscosity range. users in industry should consider this range.

There are some graphs which help technicians and engineers to choose the best available viscosity. Such assistance is useful in case gearbox OEM doesn’t mention right viscosity range.

Furthermore, users have to consider differing viscosity-temperature and viscosity-pressure behavior of synthetics.

Oils’ expected operating temperature including sump temperature and injected oil’s temperature are major basis for selecting right viscosity. In case of not installing gears, frictional losses and thermal economy should be considered but if it is installed, therefore temperature of the sump must be considered.

Also, in cold start conditions, lower viscosity are the most proper choice. Technicians should check viscosity of oil in oil circulating systems. These inspections in each existing starting temperature are useful.

Finally, calculation of the force-speed factor is a starting point as worksheet method used for spur gear drive and worm gear drives.