a4 quattro Gearbox /Torsen oil

[I_am_stealth]

Could anyone please help me choose the right oil to go into my 1.9tdi quattro manual gearbox. Gearbox code is DGW i think.
I have been having some issues changing gears, so i changed the oil. I filled it up with GL5.
Now I seem to have more issues putting it into second gear particularly when cold, but NOT always. I filled with 75W-90. I don't fully understand it. I have been reading that actually the OEM oil for the quattro has additives inside and that helps a lot. Audi charge about 15 pounds per liter or so.

What shall I do, shall I go for OEM for both gearbox and rear diff, or shall I just add something like Molyslip or other additives that reduce friction and coat the surface. Please recommend me something from your experience and make a comparison if possible.

My other worry i suppose is that I want to be sure that i don't affect anything in the way the torsen works, etc. I think I don't have any differential lock on any of the axis, it is all mechanical. The TOrsen diff gets its oil from the gerabox, doesn't it?

[carlover]

i have changed my gearbox oil twice in 2 weeks to cheapish 75w90 oil which have made the gearbox worse. I ordered redline mtl last night at £15 a liter.

[I_am_stealth]

I visited audi an hour ago. they seem to recommend exactly 75w-90 gearbox oil somewhere in their software for the DGW gearbox. However, they don't explicitly recommend that for the quattros in their software.
What gearbox do you have carlover?
I now seem to think that a smoother gearbox is down to the additives from the oil, which makes me consider buying some friction reducer and add to the oil.
I have changed to GL5 not GL4. I also read somewhere that some additives inside GL5 may damage the synchros inside gearbox.
I will either change to GL4 plus additives, or OEM..
Any more opinions? Thanks

[carlover]

buy genuine audi oil or redline mtl, that is what most people say for these old audi gearboxes.

[carlover]

i changed my gearbox oil again today to redline mtl and the shifting is smooth as silk.

[I_am_stealth]

This may be useful to many others.
I have actually checked the technical specs of various oils, not just what people describe. I think I managed to find out what OEM oil is for my car - I believe is a high spec Castrol.
Both viscosities at 40 degrees and 100 degrees are lower than the Redline MT-90.
What I have at the moment in my gearbox is Comma SX75W-90.
Both, 40 degrees and 100 degrees viscosities are lower than Redline MT-90 for this oil. I can't see how replacing the oil with a slightly higher viscosity oil will help me...Am I wrong? My car clearly shifts better when warm particularly from 1-2gear.
carlover, what oil did you put in first before changing to Redline MT-90? What car?

I am very tempted to go for Redline MTL wich is 70w-80. I don't race, so hopefully it should be ok... What do you think?

[carlover]

i used mtl.
It now shifts better than the old genuine audi oil.

[I_am_stealth]

Sorry, I have just realised that you actually changed to MTL 70w-80! I mentioned Redline MT-90 because that is recommended as being 75w-90. If you are happy with yours, and a lower viscosity is still ok, I will definetely go for it.

UPDATE:

I have finally changed both differential oil and gearbox oil to Redline MTL 70w-80. I have not posted right away just to be sure that it's not placebo...
My conclusion : It did make changing into 1st and 2nd, but particularly 2nd much easier. Third gear about the same I'd say, and 4th and 5th either the same, or maybe slightly worse. I may be talking nonsense here, but maybe friction is affected by viscosity in a different way for the different cog wheels. Overall it is a clear improvement because 4th and 5th are fairly easy to synchronize and you can give the synchro more thime to work.
I am now very rarely getting a crunch in 2nd gear. Thanks for sharing the information with me.