Your gearbox has two different big 17mm allan bolts (imbus) on it that are used to drain and fill the gearbox. Because of the dirt they can sometimes be a bit hard to find. They can both be pretty stuck, but don’t use too much force. You don’t want to damage the threads. That could get you an expensive repair. The image below shows how the plugs look:
Start by removing the top bolt (filling bolt), to be sure that you can get it loose. If you can not get it loose, do NOT remove the bottom one (draining bolt) because you will be out of oil. Then remove the bottom one and the oil will start coming out quickly. Put a big enough bucket underneath it to catch the oil. Check the oil for having big chunks of metal that can indicate a gearbox problem. Some smaller pieces of metal in your oil are normal.
Your oil drain plug has a magnetic end on it that should collect pieces of metal floating around. As long are the pieces are not very big, it is normal.
When all the oil is out you can put the bottom plug back in. Now you have to find a way to fill it from the top plug. The space is rather tight, so what usually works best is to put a piece of hose inside the hole. Then step next to your car, put a funnel inside the other end of the hose, get it up high and start putting in the oil until you get enough of the oil inside. Then close the top bolt and you are ready to go!
What gearbox oil should you use?
In total there are around 10 different types of gearboxes for the T2 and T3. They all have different filling requirements. All gearboxes can use a GL4 SAE 80 oil. Do NOT use engine oil, because it is not the same. The table below shows how much oil to use per gearbox type:
| Type of gearbox | Gearbox code | Filling amount |
| Petrol LBX 4 gear | 091 | 3.5 l |
| Petrol WBX 4 gear | 091/1 | 3.0 l |
| Petrol WBX 5 gear | 094 | 3.0 l |
| SDI & TDI 4 gear | 091 | 4.5 l |
| SDI & TDI 5 gear | 094 | 4.0 l |
| SDI & TDI 4 gear | 091/1 | 4.0 l |
| All Syncro 5 gear | 094 | 4.5 l |
| All Syncro front diff | — | 1.5 l |
| All automatics | — | ca 3.0 l |
| Automatic axle drive | — | 1.25 l |