ZF recommend LG6 for use in Ford and Lincoln 6HP26 transmissions and Ford recommends Mercon SP for the same transmissions.


This implies either-- that the Mechatronics program of Ford 6HP26 transmissions is capable of handling 2 "different "fluids, --
or ZF LG has magic properties which make it capable of being used with differing Mechatronic programs,--or there is no significant difference in the actual real life performance of LG6 and Mercon SP lubricants.


Perhaps someone could contact ZF and or CTSC which of the above would be the correct interpretation.

 

I'll be using the SP. My transmission has become exceptionally clunky in the cold weather so it needs to happen sooner rather than later.

 

And it just happened. I'll take that back. Nothing against Mercon, but I just got a gearbox fault and while I haven't seen and drips or dampness on the gearbox pan, I'm not taking any chances with the connector sleeve and if I'm dropping the pan, I'm replacing the pan as well. The kit from CTSC just makes everything easier. That said it would be slightly cheaper to buy enough SP to do a complete flush and buy everything sans oil from them, but after how messy my last home flush was I'm having a lot of trouble second guessing ZF's pan drop and fill recommendation.

 

As I reported just a few posts ago (post #160), I did contact both ZF in Germany and U.S. authorized ZF servicer California Transmission Supply Co. Neither would recommend using Mercon SP in a transmission programmed for LifeGuard 6, but they also admitted they were unaware of the differences between LG6 and Mercon SP because Ford does its own programming for its Mechatronics (possibly one of the reasons Ford gives its transmissions the extra S in the model number). I believe ZF also stated that Ford has its own transmission rebuilding operation so ZF does not see used Ford transmissions for analysis. I posted the word-for-word replies from ZF and CTSC, possibly in this very thread.

Cheers,

Don

 

So for those that have done the service per ZF's instruction, has the car always taken 5.5 quarts? I want to make sure the 6 quart kit is enough since I can't just run down to the store and pick up LifeGuard6.

 

The problem I have is that ZF appear to not be consistent in their statements.


How can they OFFICIALLY recommend the use of LG6 in Ford/Lincoln 6HP26 transmissions if they are unaware of the Ford/Lincoln Mechatronics programming? This is what they do in the attachment in my post#158 .

The early Ford/Lincoln were built by ZF in Saarbrucken--perhaps Ford had them marked with an S so they could identify them as not being built in Michigan.

 

No it varies depending on how much you drain out. I have done 2 refills on two different cars. The first one took 6L and the second one took more than 6L and I made up the extra with Mercon SP(about 400ml).This car has done about 12k miles since and is working fine.

 

Ok I'll grab an extra quart to be safe.

 

I found the reply I received from ZF in post #112 of this thread, and the reply from CTSC is in post #109.

Cheers,

Don

 

Thank you. I have read them and I understand what they say, but not the logic.

My point is that ZF recommend LG6 (from the document attached to post #158) for :

1. every BMW equipped with 6HP26,6HP26X,6HP28,6HP28X,6HP32 transmissions regardless of engine torque or power.
2.every one of the above named transmissions in vehicles built by Alpina, Aston Martin, Bentley, Ford, Jaguar, Land Rover, Lincoln and Rolls Royce, again regardless of engine torque or power.

It is inconceivable to me that Mercon SP would not perform satisfactorily in a Jaguar 6HP26.


It has also occurred to me that some late model Ford Falcons,made in Australia, are equipped with ZF 6HP26 transmissions. It would be interesting to know what transmission fluid is recommended for use in Australia.

I agree that owners should use what ever transmission fluid they are comfortable with.

 

I now have Mercon SP in my car. It's all I could get on a Sunday when I had to repair the gearbox cooler lines. I did a complete flush out of fluid using the trans built in pump and topping off via the fill hole.

No problems to note. Keep in mind that because of the situation I did not have a pan to swap in so I really didn't do this by the book at all. Mercon SP is very bright red so it was easy to tell once I had it coming out of the cooler line. It's easy to tell my leak was causing my shift problems. It was 2-3 quarts low. The 2-1 buck is gone and the shift slop has disappears. It will still mildly flare on the 3-4 shift, but goes away as soon as the car warms up.

 

If I understand the points that the representatives from both ZF and CTSC were making:

1. The auto manufacturers program the Mechatronic based on the slippage and other characteristics of the fluid they intend to be used in the transmissions installed in their cars;

2. ZF recommends LG6 in all of its 6HP26 transmissions, including the ones used by Ford;

3. Since Ford does not adhere to ZF's recommendation and instead uses Mercon SP, and Ford programs its Mechatronics based on the slippage and other characteristics of that fluid, ZF cannot comment on the suitability of Mercon SP in 6HP26s programmed by other automakers for the charactersitics of LG6;

4. The published specs for Mercon SP are similar, but not identical to those of LG6 (it's density and various viscosity ratings are all higher than LG6, though not by much); therefore it is possible, as both ZF and CTSC suggest, that Mechatronics programmed for LG6 may not behave ideally when run on Mercon SP. And even though the Mechatronic has some capacity to adapt to driving styles and component wear, it may not be able to fully adapt to different fluid characteristics. The 6HP26 is so smooth that it is possible most or all drivers might notice no difference in performance, but equally possible that some difference such as slightly more or less slippage during shifts or higher internal pressures or temperatures could lead to internal damage over the long term.

5. One of ZF's claimed advantages for the 6HP26 when it was introduced was "minimal internal tolerances," which implies that the use of a fluid with even slightly higher viscosity could require a not insignificant revision of the shift mapping in the Mechatronic, and render suboptimal performance in a box programmed for LG6 but run on Mercon SP and vice versa.

To me, just a bloke who lacks sufficient knowledge of hydromechanics and modern transmission design to make even simple assumptions, this all seems entirely conceivable. We don't yet have enough data to know if Mercon SP performs equally or is even safe for long-term use in a 6HP26 programmed for LG6.

I keep hoping a petrochemical engineer will join the forum and offer to do gas-chromatographical and mass-spectrometrical comparisons of LG6 and Mercon SP to tell us exactly how similar or different they are.

Cheers,

Don

 

A couple of observations if I may.

Notice that ZF does not say that Mercon SP is contraindicated.
They simply refuse to comment. Now if I were selling gold bars
as doorstops and had a lot of people convinced that said gold bars
held doors open much better than bricks, I would likely remain
schtum on the suitability of bricks in that role. Especially if I
could enforce full retail pricing.

There are a lot of 5HP25 out in BMW land. There is a segment
of them that watch Walmart sales on Maxlife Dex/Merc like a hawk.
When such a sale comes along, the word goes out and they strip
the shelves. Not good for me.

I use it for the Merc 722.6 found in the X308 XJR, as do various Merc,
Chrysler, and Sprinter owners using the same transmission. There are
three recommended fluids, none is the Maxlife Dex/Merc. Except in an
obscure training manual kindly leaked by someone. Mercedes has
superceded their former fluid, and some refuse to use it.

Consider that a transmission might be better served by receiving fresh
ATF on a regular basis as compared to the same transmission where the
owner stretches the changes due to the cost of the annointed liquid gold.

Viscosity variance within reason should be acceptable. The transmission
has to operate at wildly varying temperatures. Viscosity varies as a function
of temperature. The perfect viscosity at one temperature might be not so
perfect 20*C away from that point.

Viscosity is a holy war on the motor oil front. I use 15W40 and have good
reason to do so based upon science that is accessible to all. Yet, the "read
the manual" crowd will not read the science when cited, and will not consider
that the factory recommendation is peppered with weasel phrases and directed
at their own corporate reality.

 

I feel like I'm taking ZF's stance even though I do have SP I'm my gearbox. To be fair it hasn't been in there for a full week yet and that's way too short to know if it would be an issue. At a certain point I decided I wouldn't deviate from LG6 which was different from my original decision to use the SP, but when things happen and decisions have to be made in short notice to get the car back on the road SP is somewhat hard to find but still attainable from local part stores. O'Reilly's had it here, but I had to go to two stores to get enough for a full flush and it was kept in their back stock room instead of on the shelf.

Anyway, this thread is going in circles and neither CTSC or ZF are ever going to endorse SP for obvious reasons. LG6 is an excellent and proven product and it would be risky to suggest using otherwise without extensive testing.

I would put it this way. Use your gut because you'll never get a definitive answer from one of these sources on Mercon SP. If you feel comfortable using SP, do it. If you are concerned there could be an issue and you fear you'll worry about the longevity of your gearbox from not using an approved fluid, then use the LG6 recommended by the manufacturer.