Oils for gearbox and rear differential MB ur

BackintheFold · 26-06-23, 03:21 PM

As title, what are people using for these? I want to check/top up mine-not necessarily drain it all out and refill-although that may be an option.

Thanks!

tractor Dave · 26-06-23, 04:49 PM

Castol syntran 75/90 gl4 in the gearbox. Castrol transaxle EP90 gl5 in the rear diff. Change them both. They will be grotty.
Do not use a gl5 oil in the gearbox as it will eat your brass synchros.

BackintheFold · 26-06-23, 05:05 PM

Cheers Dave. I need to flick through the service history before I decide whether to drain it all.

BackintheFold · 04-07-23, 12:36 PM

Another Q...can I use GL4 in the rear diff? Just to top up? Would it mix with GL5?
Still finding time to check the service history for details of the last fill up.
Thanks.

tractor Dave · 04-07-23, 02:17 PM

It's not the right spec for the diff.

BackintheFold · 04-07-23, 02:20 PM

Quote:

Originally Posted by tractor Dave

It's not the right spec for the diff.

Agreed,
But will it blend?

(If I used it it would be as a top up rather than a refill)

EDIT-to put it another way, which is better for diff-75% full of GL5, or 75% full of GL5 and 25% full of GL4?

Now that I've written it down, I think its clearer-75% would be best-the GL4 would act to "dilute" the GL5.

Even better-£15 on a litre of GL5.

tractor Dave · 04-07-23, 04:28 PM

You've answered your own question. These cars are too special to skimp on.

BackintheFold · 04-07-23, 08:31 PM

It’s no so much the £, it’s that I have 2 litres of gl4 and the diff was apparently filled 4 years ago. I just want to ensure my fluids are done. It’s almost guaranteed that I’ll spend 20 minutes getting it up on ramps and level, to find it’s actually full.
Then I’ll have 2 litres of gl4 and a litre of gl5 on my shelf for the next 10 years…

But yes. I am buying it.

BackintheFold · 11-07-23, 10:09 AM

I got the car up on ramps at the front, axle stands at the rear and level.
Put about 300ml in total to gearbox and rear diff.
So they were basically full anyway-but at least I know this now.

26-06-23, 05:05 PM	#3
BackintheFold Senior Member Classic Audi Club Member Join Date: Feb 2019 Location: Near an MB ur Quattro Posts: 1,188	Cheers Dave. I need to flick through the service history before I decide whether to drain it all. __________________ 2006 A3 (daily drive) 1987 MB ur

04-07-23, 12:36 PM	#4
BackintheFold Senior Member Classic Audi Club Member Join Date: Feb 2019 Location: Near an MB ur Quattro Posts: 1,188	Another Q...can I use GL4 in the rear diff? Just to top up? Would it mix with GL5? Still finding time to check the service history for details of the last fill up. Thanks. __________________ 2006 A3 (daily drive) 1987 MB ur

04-07-23, 08:31 PM	#8
BackintheFold Senior Member Classic Audi Club Member Join Date: Feb 2019 Location: Near an MB ur Quattro Posts: 1,188	It’s no so much the £, it’s that I have 2 litres of gl4 and the diff was apparently filled 4 years ago. I just want to ensure my fluids are done. It’s almost guaranteed that I’ll spend 20 minutes getting it up on ramps and level, to find it’s actually full. Then I’ll have 2 litres of gl4 and a litre of gl5 on my shelf for the next 10 years… But yes. I am buying it. __________________ 2006 A3 (daily drive) 1987 MB ur

11-07-23, 10:09 AM	#9
BackintheFold Senior Member Classic Audi Club Member Join Date: Feb 2019 Location: Near an MB ur Quattro Posts: 1,188	I got the car up on ramps at the front, axle stands at the rear and level. Put about 300ml in total to gearbox and rear diff. So they were basically full anyway-but at least I know this now. __________________ 2006 A3 (daily drive) 1987 MB ur

26-06-23, 04:49 PM	#2
tractor Dave Senior Member Classic Audi Club Member Join Date: Apr 2018 Location: Wales Posts: 1,174	Castol syntran 75/90 gl4 in the gearbox. Castrol transaxle EP90 gl5 in the rear diff. Change them both. They will be grotty. Do not use a gl5 oil in the gearbox as it will eat your brass synchros.

04-07-23, 02:17 PM	#5
tractor Dave Senior Member Classic Audi Club Member Join Date: Apr 2018 Location: Wales Posts: 1,174	It's not the right spec for the diff.

04-07-23, 04:28 PM	#7
tractor Dave Senior Member Classic Audi Club Member Join Date: Apr 2018 Location: Wales Posts: 1,174	You've answered your own question. These cars are too special to skimp on.