Is gearbox oil really that important? Keeping your car’s engine and its various components lubricated is essential to maintain smooth running and reliability, but there’s more to it than just keeping an eye on the engine oil. There are many other important parts which require the correct lubricants to function correctly, including the gearbox. There can be some confusion over whether you need gearbox oil or transmission oil for your car. To be honest, it’s a question that’s quite straightforward to answer: if your car is manual, you’ll need gearbox oil; if it is an automatic car, you’ll need transmission oil.
There are many complex moving parts inside a gearbox that need lubrication not only to ease movement and reduce friction but also to dissipate heat. Regularly replacing the gearbox oil will mean that your gear shifts are smooth and quiet and reduce running costs.
Looking for the best gearbox oils can be a tricky sea to navigate, though there are many different options to consider. Do you need natural, semi-synthetic or synthetic gearbox oil? Your first port of call should be your car’s owner’s manual. This will tell you what gearbox oil it recommends, and then stick to that. If you’re still unsure what to use, Amazon Garage (below) has a convenient tool to help you figure it out, and your local motor retailer will undoubtedly be able to help you out, too.
Below, we look at the best gearbox oils you can get for manual transmissions.
Best gearbox oil at a glance:
Editor’s choice: Castrol Transmax Multivehicle – Buy now from Amazon UK
Best for heavy-duty use: Motul Motylgear 75W-90 – Buy now from Amazon UK
Best for budget: Comma SX1L 1L SX75W-90 GL-5 Semi-Synthetic Gear Oil – Buy now from Amazon UK
Best gearbox oil
Pros
- Easy to use
- Order from home
Cons
- May need an Amazon Prime subscription for free delivery
Editor's choice
Pros
- Performs well in colder conditions
- Enhances transmission life
Cons
- None
Best for heavy-duty use
Motul formulated Motylgear 75w-90 as an extreme pressure lubricant for efficient anti-wear protection and reinforced it with synthetic base stocks for better resistance at high temperatures and longer life.
Pros
- Great for heavier vehicles
- Versatile use
Cons
- The pouring spout could be improved
Best for budget
Comma Oil and Chemicals was founded on a real ‘passion for performance’ in 1965 as a UK-based, independent oil 'blender'. Quickly establishing their products as the first-choice supplier of engine oils to independent workshop mechanics in the UK, Comma has recently grown to distribute to more than 40 other countries worldwide.
Pros
- Suitable for different GL5 applications
- Good value
Cons
- None at the price
Best for multiple uses
This gear oil is capable of performing well, even during large fluctuations in temperature, giving great resistance to the signs of ageing on the gears.
Pros
- Inhibits component ageing
- Great for temperature fluctuations
Cons
- Oil can drip from the spout
Best specialist oil
Pros
- Ideal for recommended marques
- Improved performance
Cons
- Needs to be pre-ordered
When should I change my gearbox oil?
Manual transmissions should have their oil changed every 30,000 – 50,000 miles or after five years. This differs from car to car depending on its use; if you carry lots of heavy goods or towing constantly, it would be good to get the oil changed more frequently because of the excess strain you are putting on the gears.
Equally, if you allow engine speed to get excessively high too often, you’ll need to be more frequent in your oil changes to allow for the extra pressure you’re putting on the gears.
Over time, gearbox oil can become contaminated with particles, dirt, and metal shavings. Regular oil changes help remove these contaminants, preventing them from causing damage to the transmission components. If you’re looking at high-mileage gearbox oils, a gearbox oil change will probably be in order.
Following the manufacturer’s recommended service intervals for gearbox oil changes is the best advice. Manufacturers provide these guidelines based on extensive testing to ensure the optimal performance and durability of the transmission.
Replacing your gearbox oil at recommended intervals is a proactive measure to ensure the proper functioning, durability, and efficiency of your vehicle’s gearbox. It helps prevent damage, reduces the risk of costly repairs, and contributes to the overall reliability of your vehicle.
Ryan Gilmore is the Deputy Autos and Tools Editor for Parkers and CAR, specialising in car cleaning and hand tools. With an MA in Automotive Journalism, when he’s not testing buckets he can be found looking at old Porsches.
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