dvs_dave

tl;dr Literally any ATF that meets Shell M-1375.4 specs is all that’s needed. Many options out there. Don’t waste your money on the ZF/VAG branded stuff.

There's always been a lot of confusion and misinformation posted about this so I thought I'd contribute some new information I've recently found out on the topic. It's a long post but hopefully worth the read.

Setting the scene

The 6-speed 09E transmission as used in all quattro D3 A8's is actually a ZF 6HP26 (6HP19 for smaller engine versions) unit. The quattro drivetrain parts (TORSEN center diff, drive shafts and front diff) are all bolt on accessories to this core transmission. The ZF 6HP range of transmissions is used by many OEM's ranging from Rolls-Royce to Hyundai, and is on the whole a very strong and reliable unit.

The official line from both ZF and Audi (and all other OEM's) is that the units are maintenance free and have a lifetime ATF fill. What "lifetime" actually means has never been quantified. However problems with the transmission developing a "hoot" noise when changing between gears 3-4 has become a common issue for many owners. The official service remedy from all OEM's affected has been to change the transmission fluid. The details of the Audi specific TSB for this can be found here, but it's essentially still just a fluid change rolled in with a software update that later cars had from the factory anyway.

Because this was a widespread issue, ZF changed their position on the lifetime fill specification for the 6HP. They now somewhat sneakily advise that "depending on driving style", the transmission fluid should be replaced every 8 years or 80k miles to maintain optimum performance. See here for the the official ZF Service Bulletin on the matter.

Despite this, Audi has not changed their position on the "lifetime" ATF. Therefore it would seem that Audi regard 8yrs/80k miles as beyond "lifetime".

Transmission Fluid / ATF Specs

So that brings us to the topic of ATF for the 6HP.

The official line from ZF is that only their "Lifeguard " branded ATF, or vehicle OEM equivalents can be used (e.g. VW G055 005), with a stern warning that other fluids will damage the transmission. The ZF specification group that these ATFs come under is ZF TE-ML 11.

However the Lifeguard 6 ATF variant (aka LF6, VW G055 005) used in most applications of the 6HP is unreasonably expensive. So over the years it's become clear that the base quality/spec standard is Shell ATF M-1375.4, and below are some of the numerous cheaper equivalent options that are available now:

Redline D6 ATF
Liqui Moly Top Tec 1800
Shell Spirax S4 ATF MSP
Mercon SP
Ardeca Matic +Z6
Motul ATF VI
Ravenol ATF 6HP
Anything else that meets the Shell ATF M-1375.4 specs

Some models specify a different fluid, namely the W12, and the 6 cyl models using the 6HP19 lower torque capacity version. Initially this was Lifeguard 6+ (VW G055162A2) which was blue in colour and has been discontinued. It was rebranded to coincide with the new range of 8-speed 8HP transmissions as Lifeguard 8 (VW G060162A2) and the colour changed to green. It's the same stuff though, just dyed green instead.

The base specification for this is Shell ATF M-L12108 So suitable equivalents to VW G055162A2, VW G060162A2, LF8 are:
Ravenol ATF 8HP
Ardeca Matic 8HP
Redline D6 ATF
Not as many obvious ones as it's a newer product, but anything that meets Shell M-L12108 is the key

So far I have not shared any new information, or knowledge that's not readily available. But I recently found out some very interesting new info on the topic.

You're probably thinking who the heck are Ardeca? Well they are a Lube company from Belgium, and they had a stand at the recent Automechanika 2015 tradeshow in Chicago that I attended. As did ZF.

ZF were exhibiting their ATF service kits and when I inquired further, the reps were towing the official "depending on driving style" line about ATF changes. However when I pressed them on it, they tacitly admitted that 80k miles is when you should do an ATF change on the 6HP, regardless. They would not however be drawn on any equivalents to LF6, stating that only LF6 (or LF8 depending on application) has the correct composition and additive packs to not damage the transmission. There are stern warnings stating this both in ZF literature and also on the labels of LF6 bottles.

So moving on, I got talking to the guys on the Ardeca Lubricants stand as they had a product (MATIC +Z6) that specifically stated was for the ZF 6HP. As it turned out I was talking to the head of Ardeca and I asked him how he can be selling an ATF labelled as specifically for the the ZF 6HP, when ZF, just 3 stands away said there are no LF6 equivalents, and anything else will cause damage.

He laughed and said it was simply nonsense and scaremongering by ZF. He went on to confirm that the base specification is Shell M-1375.4, and that until a few years ago, ZF held the licence on the additive pack for M-1375.4. Consequently they licensed it out to ATF makers for an extortionate sum. As it happens, most OEM specific ATF (e.g. VW G055 005) for the 6HP is not repackaged Lifeguard 6, rather an equivalent made to the same M-1375.4 specs. He said that his company itself had to pay this licence to fee to ZF for the additive pack for many years, which in turn made their ZF LF6 equivalent very expensive back in the day.

He then went on to explain that the ZF licence for the Shell M-1375.4 additive pack is no longer valid and the "recipe" is now freely available on the open market. Hence why there are now numerous ATF's out there that claim to be LF6 equivalents but for a fraction of the price. And here's the kicker, he said that it can be dyed any color you like, green, blue, red, whatever...

So there you have it. Draw your own conclusions, but for me the overwhelming evidence points me well away from the belief that LF6 is anything special, or worth paying any sort of premium for.

Happy DIY ATF changes for less than 75 bucks!

ETA: I've since done a fluid and filter change using Redline D6 and it improved things considerably. https://www.audiworld.com/forums/a8-...ected-2883008/

MP4.2+6.0

Good write up.

For those who want more info and decide for themselves, Google "ATF M-1375.4". ZF used to cite to the fluid manufacturer spec (since they don't manufacture oils), but I notice these days I don't seem to see them tying to it for the various different ZF flavors from the 5, 6 and 8 speed generations. Back with my 2000 A6 4.2 with the five speed ZF, they clearly used to from my own use of the information from their site in that era (that was Esso LT71141). Might fit into the disappearing patent angle in OP's discussion.

If you Google to the spec, you will quickly find a variety of materials on the subject, support for OP's information and some varying perspectives. As I found with the transmission internals, in general there is a lot more information, posting and perspectives involving BMW fitments of the same basic ZF tranny (less the AWD adds as OP mentions). Rather than repeat the discussion and debates here, readers with an interest may want to look at those materials.

Personally I still prefer manufacturer spec sheets and related technical materials to oral information, at least to validate something. In that vein, here's a Shell data sheet that ties between the (Shell) ATF M-1375.4 fluid spec and the Ford/Mercon SP spec./teminology: http://www.epc.shell.com/Docs/GPCDOC...en-CA)_TDS.pdf That (and other info) can be found with the same Google ATF M-1375.4 search. It also has a passing reference to "Filled for life potential in ZF automatic transmissions." Once you decide on equivalency to Mercon SP, in turn of course you get to a way different fluid price point.

Not expressing a particular opinion here other than having usual questions about additive packs, but I continue to share source information for folks to read and judge for themselves.

allenst

Great piece.
now for a newbie question.
would you just drain and fill ?
or
would you do the filter too ?

dvs_dave

At the 80k mark I'd do a filter and ATF change.

dvs_dave

Found this video by ZF detailing the ATF change procedure. It's for the plastic pan variant with integrated filter (Audi use metal pan with separate filter), but the steps are the same.

ZF Friedrichshafen AG | ZF 6HP Oil Change Procedure

richard-tx

Here is an interesting quote from ZF.

"ZF currently has several fluids used for various 6HP applications. A good example is Audi who recommends fluids by vehicle model not transmission model. This may be due to the demands of the specific vehicle such as smooth shifting VS performance orientated driving requiring faster shifts and better heat control. The friction coefficient of the fluid is programmed into the transmission controller. Changing fluid type will affect the calculation and ultimately drivability. This, in a worst case scenario could lead to transmission failure."

Now I know why the dealer asked for VIN number when buying ATF oil for my 2006 A8.

dvs_dave

Yes, on that point it's referring to the use of LF8 as the factory fill in certain models. Only Audi appear to do this and it's specific to the A8 W12 and Q7 models only. All others use LF6. Incidentally the TSB for the hoot on W12 and Q7's says change the fluid to LF6, no software update required.

LF8 is also the factory fill for the 8-speed ZF 8HP used in newer vehicles.

There are LF8 alternatives out there as well (e.g Ardeca Matic 8HP), and others like Redline D6 that are compatible with both.

It's clear that LF6 and LF8 have different overall properties (namely viscosity bands over their life), but there is a common overlap in those specs. That means that products like Redline D6 are engineered to work only in that specific overlapping viscosity range which is why they are suitable for both LF6 and LF8 uses.

MP4.2+6.0

On bringing in the 2006 and being asked for the VIN, I'll give a somewhat different take. First, as stated it can be that it is the W12/everything else split. But that is also obvious from the motor. Nonetheless they do know the motor as soon as they enter the VIN, along with everything else specific to the car build and specs.

Here there is another nuance though. Audi service records should also tie in so they should also know if the tranny was recoded. If so with a 4.2, they will sell you either blue (LG 6+) or green (LG8). Audi still sells blue (6+) unlike ZF, so they could trot that out, and likely would if the VIN says W12.

It doesn't stop just with A8's, but rather seems fairly unique to a class of Audi's subject to the TSB involved/ Most of them were V8's with the six speed, though there were A4's in the group as well that I don't have an easy answer for. Here's the TSB and you see the vehicles listed at the top: http://uberlame.com/a6_tsb/Transmiss...2037-06-13.pdf Thus on that set, to be sure you also need to know what happened service wise. For most Audis, they go the whole model run with the same tranny, but there have been exceptions; in those cases the fluid may change because the basic unit changed. It often but not always goes with a motor change, like when the 3.2's and (some) 4.2's got swapped out for 3.0T's and the six speed became the eight.

I'll also differentiate between viscosity and additive pack. A fluid change may or may not involve a viscosity change, and may also involve an additive pack. The former may be picked up in an underlying industry spec., the latter perhaps less so. An additive may be a friction modifier, which may not really be viscosity related. LG 6 was understood to be a lighter viscosity than LG 5 for example, but I'm unaware of that for 6+, and don't recall it being described as such for LG8. ZF/Audi have always been mum about what exactly was in 6+ (compared to 6), but I've always wondered/suspected if it was a slight additive pack tweak with a die change, later essentially subsumed by LG8 that used another die. In the W12 specifically, with the same underlying programming, Audi has you using LG6+ while ZF has you using 8. That's maybe a clue. In another world, having owned a Chrysler when they went to a 4 speed from a 3, lots of folks put the wrong fluid in--called ATF+4 instead of the old Dextron. What they got was a squeal. ATF+4 was also understood to be a different additive pack involving a critical friction modifier, and here made a difference for a bunch of owners. Also having owned the lemon ZF 5 speed, there was a parts store additive sold (Redline?) tied to a super obscure GM/Saab TSB that said use this store bought additive if you had certain shifting issues. Folks then sometimes adopted it for other ZF units even though they were different; another example of literally an "additive pack."

Finally on the programming, again the oddball W12 is a bit the revealing case. So if you read the attached TSB, it says for the W12 change the fluid--still to blue/6+--but flash it. So, saying it explicitly, for that one, same fluid, but flash. Hmmm. For years the TSB sat that way. Later they amended it to say if you flash the tranny in a W12 then backward migrate to 6, but it's hard to even find the late version of the TSB on the web. So, did they make a "mistake" that sat then for years? Did they call any back they did the "old way" with 6+ still? (not that I ever head of). And BTW, of course they built many A8's in both 4.2 and W12 flavor after the affected production years (only through 2006 per TSB) with the same fluid as always, yet with presumably something tweaked. Huh? If anything, I have concluded its an argument that there is a modifier change as between the 6 and 6+ fluid choices (and now maybe 8 given the Audi/ZF split here) and the flash software change may also help, but honestly they may have been kind of throwing stuff at the wall to see what stuck as they say. And for what it's worth, I have the formerly legit and now theoretically "bastard child" mix--I changed the factory fill 6+ myself (leaving it 6+), and had it flashed on request at Rector Audi. Service guys had no issue doing it that way. And FWIW, my guess is I have what the 2007-9 W12's actually do--blue fluid (known) and updated software (guess). With my Mechatronics seal replace and solenoid change--done with a ZF kit ordered by 3 digit ZF tranny code--I do know it shifts like factory new.

allenst

your second last line..."Changing fluid type...."

I'm thinking a ATF that's been rolling around in Tran for 10 years is in fact a "changed fluid" It's properties cannot be those as the day it hit the road for first time.
A litre of brand new ATF beside a litre of 5 year old ATF beside a litre of 10 year old ATF. IMO they would all have different physical makeups.

Alexxelax

When i search in a shops data base with my licence number i get o few oils wich 2 are

Castrol transmax z

Castrol mtx full synthetic 75/140

My Q are, is anyone familiar with this oils and have used them? How do you think about the oils in a audi S8 transmission?

and when driving it feels like it spins a for a second before shifting, may a oil change make it better or is it already to late? It drives good and its just in low speeds it feels like it take a while before shifting, also the rpm bounces up and down little.

Car is S8 2006 180.000km and as i know no ATF has been changed