Gearbox dripping oil

Evening all,
Urgent problem with my cabby Gti! It’s booked in for its mot next week and I’ve just found an oil leak coming from between the gearbox and driveshaft on the passenger side. It’s definitely gearbox oil which means it will fail the mot.
Its a 5 speed 020 gearbox on a 1987 DX Gti and I’m guessing it’s the gearbox drive cup seal part no.020498085G that has failed?
Is it worth doing the gearbox seal housing at the same time? I’m guessing the parts are the same for both sides of the gearbox so while it’s out is it worth doing them both?

Need to order the parts this weekend so any help would be much appreciated!
Cheers

Depends how bad the leak is. Not sure a slight drip is a MOT fail, most older cars would fail if that was the case, might get an advisory.

Having said all that losing oil will eventually wreck the box so the seal will need replacing, perhaps not just in a mad rush for the MOT?

It's probably the flange seals which have gone hard over time, you can change them with the gearbox on the car but it is easier with the gearbox on the bench.

Guide here.

020 Flange

You could clean most the oil off the gearbox and send it in for an MOT and you maybe just come away with an advisory, I've done that before and for a few years till I got around to changing the seals, I just topped up the oil every few months. 

Thanks for the replies!
Yeah I would like to get it sorted before it does any damage to the gearbox although it looks like a very slow leak. I think the seals have done well considering they are most likely original items.

Great guide  Just completely out of my comfort zone with doing stuff like that  I did the clutch once….never again
I will get the seals ordered and let the garage do the work!

You will only damage the gearbox if you let the oil level drop to low….


It maybe a good idea to switch the gearbox oil to fully synthetic when they change the seals as they will need to drain the oil before doing the job.

I've been using this stuff in both my cars for a few years and very happy with it as it stopped my 2nd gear crunch when the gearbox was cold.

2 x 1 litre bottles is plenty as I've only ever managed to get about 1 and 3/4 bottles in my gearbox.

https://www.eurocarparts.com/p/triple-qx-75w-80-api-gl4-5-fully-synthetic-1-ltr-522776282

The 5th gear is splash driven, if you get it too low then you will burn out your 5th gear.

I would replace both seals.

Are you sure it's not leaking where the speedo cable enters the gearbox then running down.

Just had a really good look, the rest of the gearbox is dry but the seal is very wet with oil.
The part number that I put up in my previous post- is that the correct part?