Do I need a manual gearbox oil change?

It depends on the vehicle. Some manufacturers set a gearbox oil change interval, others describe the oil as fill-for-life, and many owners and garages still prefer to renew it on a higher mileage car. There is no single answer, which is why this guide explains the reasoning so you can ask the right questions.

What is certain is that gearbox oil does real work. It reduces friction between gears, protects the bearings, helps the synchromesh to do its job and carries heat away. When it is worn or low, the gearbox feels and sounds worse, and wear speeds up.

What does gearbox oil actually do?

Inside the box, gears mesh, shafts spin on bearings and synchro rings match speeds. All of these surfaces need a film of oil. Over many miles the oil shears and takes in tiny metal particles, so it protects less well.

It is a different oil from engine oil. Gearbox oils are made for gear loading and for the friction needs of the synchromesh, which is why using the wrong one can cause stiff shifts or damage.

How often should a manual gearbox oil be changed?

Check your handbook or service schedule first. Some makers list a distance or time interval, some say no change is needed under normal use, and some are silent. Heavy use, such as hauling heavy loads, regular short trips or lots of stop-start traffic, can be harder on the oil, and a higher mileage car that has never had a change may benefit from one.

One caution: on some gearboxes that have gone a very long way on the original oil, a change is not always a cure, and a garage will weigh up the car before advising. We would rather look first than give a blanket rule.

• Handbook interval, if there is one
• Age and mileage of the car
• How it is used day to day
• Any noise, stiffness or leak

What are the signs the oil is low or tired?

A whine or hum, stiff or notchy shifts, especially when cold, and oil marks on the underside or driveway can all point that way. A seal leak can leave the gearbox low without much visible mess.

Low oil is a worse problem than old oil, because bearings and gears run short of lubrication. If you notice any of the signs above, have the level checked rather than waiting for the next service.

What happens during a gearbox oil change?

The car is raised, the drain plug is removed to let the old oil out, and we look at the condition of the oil and plug for metal debris. The plug is refitted with a new washer where one is specified, and the box is refilled with the oil grade the vehicle calls for, to the correct level.

The amount and the way a gearbox is filled differs from car to car, and on some the filler is awkward to reach, which affects labour time. Cost depends on the oil specification and quantity, access, and whether any seal or leak needs attention. We give a quote on request.

Why use a garage rather than doing it myself?

The job looks simple, but the details matter: the right oil grade, the right fill level, and noticing what the old oil tells you. Overfilling or underfilling both cause problems, and old oil must be disposed of properly.

If the old oil shows glitter or heavy contamination, a garage can advise whether an inspection is sensible. And if there is a leak, it is found and dealt with at the same visit rather than discovered later.