Gear Oils

Repco offers a comprehensive selection of gear oils designed to suit a wide variety of vehicles and driving conditions. Whether you need diff oil for your differential, gearbox oil for your manual transmission, or specific grades like 80w90 gear oil or 75w90 gear oil, Repco stocks trusted brands and formulations to keep your drivetrain running smoothly. Choosing the right gear oil is essential for protecting gears from wear, reducing friction, and ensuring reliable performance under load. The range caters to both everyday drivers and automotive enthusiasts who demand consistent quality and protection. Clear product information and expert advice make it easier to select the correct oil for your vehicle’s requirements, helping maintain optimal operation and extend component life.

How often should gearbox oil be changed?

Gearbox oil, also known as gear oil or manual transmission fluid, should generally be changed every 40,000 to 60,000 kilometres, depending on the vehicle manufacturer’s recommendations and driving conditions. For vehicles used in severe conditions such as towing, off-road driving, or frequent stop-start traffic, more frequent changes may be necessary. Regularly changing gear box oil ensures proper lubrication of gears, reduces wear, and prevents overheating. Using quality products like Penrite 80w90 or Castrol vmx 80 helps maintain optimal performance and extends gearbox life. Always consult your vehicle’s service manual for specific intervals and specifications.

Can I use engine oil as gear oil?

Engine oil is not suitable as a replacement for gear oil or diff oil. Gearbox oil is formulated with specific additives and viscosity properties to handle the high pressure and shear forces within gear sets and differentials. Engine oils lack the extreme pressure additives required to protect gears from wear and pitting. Using engine oil in place of gear oil can lead to inadequate lubrication, increased wear, and possible gearbox damage. It is important to use the correct gear oil grade such as 75w90 or 80w90 gear oil, as specified by the vehicle manufacturer.

What is the difference between 75W 90 and 80W-90 gear oil?

The numbers in 75w90 and 80w90 gear oil refer to the oil’s viscosity rating at cold (winter) and operating temperatures. The 'W' stands for winter, indicating the oil’s flow at low temperatures. 75w90 gear oil has a lower cold temperature viscosity than 80w90 gear oil, meaning it flows more easily during cold starts. This can improve lubrication on start-up and reduce wear in colder climates or conditions. Both oils maintain similar viscosity at operating temperatures, providing effective protection under load. Choosing between these depends on climate, vehicle requirements, and manufacturer recommendations. For example, 75w90 is often preferred in modern manual transmissions and differentials for better cold start performance.

What is the difference between a GL4 and a GL5 gear oil?

GL4 and GL5 are API classifications indicating the level of extreme pressure additives in gear oils. GL4 gear oil contains moderate levels of additives designed for manual transmissions and some differentials where yellow metals like brass or bronze are present. It provides good protection without excessive corrosion risk to these metals. GL5 gear oil has higher concentrations of extreme pressure additives, suitable for hypoid differentials and heavy-duty applications, but it can be corrosive to yellow metals if used improperly. Using GL5 gear oil in a gearbox designed for GL4 can cause premature wear of synchronisers or brass components. Always use the gear oil grade recommended by the vehicle manufacturer to ensure compatibility and protection.

Does it matter what gear oil you use?

Yes, selecting the correct gear oil is important for the longevity and performance of your gearbox and differential. Using the wrong viscosity or API classification can lead to insufficient lubrication, increased wear, and potential mechanical failure. For example, using SAE 90 gear oil where a 75w90 or 80w90 gear oil is specified may cause poor cold start lubrication or overheating. Similarly, using GL5 gear oil in a system designed for GL4 can damage synchronisers or brass components. Products like Penrite 80w90 or Castrol vmx 80 are formulated to meet specific standards and should be chosen based on your vehicle’s manual. Regularly checking and using the correct diff oil and gear box oil helps maintain smooth shifting, reduce noise, and protect gears under load.

Completing Your Vehicle Maintenance with Repco

Alongside gear oils, Repco provides a variety of complementary products to support vehicle maintenance and performance. Engine oils help keep your engine running efficiently, while fuel additives improve combustion and fuel system health. Cooling system products assist in maintaining proper engine temperatures. Together with quality gear oils like 75w90 and 80w90 gear oil, these categories offer practical solutions for keeping vehicles in good condition, whether for daily driving or more demanding automotive tasks.