How to change gearbox oil | Gear oil replacement

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  • OVERALL DIFFICULTY INDEX: 3/10
  • IF YOU NO TOOLS YOU PAY $15 TO GET THEM FOR THIS JOB
  • IF YOU HAVE NO EXPERIENCE YOU SPEND 1 HOUR TO CARRY OUT THIS JOB
  • RISK OF ALLERGY FROM CONTACT WITH GEAR OIL
BEFORE YOU START
Make sure to wear gloves and not to let the transmission fluid get in contact with your skin or spill on the floor, observe good hygiene while carrying out this work.
DISCLAIMER:
Our pictorials are of informative nature and do illustrate works carried out by ourselves at our own premises for our own use and satisfaction.
Readers who envisage to carry out similar works inspired by the below method shall do this at their own risks and liability.
NOTE: the below works are shown on a Peugeot 208 1.2 equipped with a manual gear. Works remain much similar or else identical on any front wheel drive vehicle fitted with a transverse engine and manual gearbox.

When to change gearbox and differential oil?

You have to follow you car's recommended gear oil change intervals and stick to the recommended specification for the manual or automatic transmission fluid.
In case of absence of any indication, it is considered that gearbox oil should be changed every 100,000 Km.

Draining the gearbox oil

Look well at your gearbox and/or differential in case of a FWD vehicle and find the gearbox drain plug which looks like exactly an engine oil plug. Some gearboxes could have two plugs, one for draining, one for refilling. The one for draining the gearbox is indeed the lower one. FWD vehicles will have both the gearbox and the differential drained at one time from the differential oil plug.

Place a bucket beneath the gearbox and unscrew the drain plug while taking care not to let the gearbox oil splash on you.
Let it drain for a few minutes.

Refilling the gearbox

Replace the washer of the gearbox drain plug with a new one and refit the plug to the gearbox or differential with your hand until contact.
If you used a compression copper seal (washer) continue tightening the gearbox plug until the copper seal is compressed, i.e. its thickness is reduced by 2/3.
If you're using a non-compressible plug seal, just tighten by 3/4 of a turn.
Take out the gearbox refill plug which can be on either:
  • the top of the gearbox as shown here in this FWD vehicle
  • the side of the gearbox, above the drain plug

Refill gearbox oil using a funnel for the first case described above or a funnel prolonged with a transparent tube for side mounted plugs.
Proceed as follows:

1- Top mount gearbox oil refill plug:
Add the exact quantity of gear oil (transmission fluid), as given in your car manual. Use the recommended gearbox and differential lube but almost all manual transmission require 75W90 or 80W90 gear oil, which can be either mineral, semi-synthetic or synthetic like for engine oil.
​
2- Side mounted gearbox oil refill plug:
Add the transmission fluid little by little until it reaches the gearbox refill opening and starts flowing out.
Let any excess gearbox oil drain out until reaching a drop-by-drop flow then refit the plug with a new seal.

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