Molub-Alloy GM 690/320

Gear oils

Castrol Molub-Alloy GM™ Gear oils (Previously called Molub-Alloy™ Gear oils) were developed for the lubrication of enclosed gears.

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  • Product category Gear Oils
  • Sub-category Mineral Enhanced
  • Application Shock Load


Castrol Molub-Alloy GM™ Gear oils (Previously called Molub-Alloy™ Gear oils) were developed for the lubrication of enclosed gears. They are manufactured from the highest quality components that have been carefully selected for their compatibility with Molub-Alloy GM lubricating solids.
Load carrying capabilities are derived from Molub-Alloy GM's formulation and the proprietary blend of lubricating solids.
The lubricating solids are treated to increase their natural affinity for metal surfaces. Also, they are completely dispersed to assure effectiveness over the life of the oil.
Rust and oxidation inhibiting characteristics are maximized to afford effective rust protection and long service life.

Molub-Alloy GM gear oils are recommended for spur, helical, herringbone, and straight or spiral bevel gears. They are especially suited for heavy duty and shock loading where Extreme Pressure (EP) characteristics are required.
They should not be used where gear manufacturers specify the use of non-EP lubricants. For severe worm gear service where ‘compounded’ gear oils are recommended please refer to Molub-Alloy GM 170w / 680.
Molub-Alloy GM gear oil 300 S / 1000 is especially suited for service in enclosed gears for heavy-duty industry and mining machinery.

Reduced friction, most evident under boundary conditions, is directly attributed to the presence of specially compounded lubricating solids. This benefit is most pronounced where frequent start-up, slow speeds, and high
and unexpected loads are encountered.
The establishment of a protective layer of Molub-Alloy GM solids provides substantial increase in the working life of both parts and lubricant. This increases load bearing area which can reduce unit pressures operating
temperatures, and wear.
Realistic energy savings are possible through a reduction in peak power demand during cold start-up.
Seal leakage is greatly reduced. Only compatible base oils that control rubber swelling tendencies are used. The Molub-Alloy GM solids lubricate and improve seal contact surfaces.
Overall savings are derived from the above and result from less labour and downtime, smoother, more efficient operation with longer parts life, and extended lubrication cycles


Viscosity 320 mm/s² at 40°C
Oil type Mineral
Product type Lubricating Oils
Applicable to these sectors Aerospace, Automotive Manufacture, Cement, Chemicals, Engineered Wood, Machinery, Metal Goods, Metals, Mining, Pulp & Paper, Sugar
This product is replacing Molub-Alloy 690/320 Heavy duty/shock loaded gear oils

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