Hi Don
I did not experience any unusual noises or other characteristics when filling either of my gearboxes. My belief is that they did not run under load during the filling process so damage would not have occurred. Although pump cavitation is a potential issue if the fluid is aerated I do not consider this would be an issue for the relatively short period the gearbox pump and internals run during filling.

I will share some other observations:-
The gearboxes had 116000(MY 2004.5 XK8) and 59000 (MY 2003 S type R) miles on them respectively when I changed the fluid filters and seals. Visually there was a minor leak from the sleeve on the high mileage box. From the dates on the removed filters neither had been serviced. The build up on the magnets was visually identical for both filters. The fluid was dark but did not smell excessively.

I used a scissor lift and ensured the cars were level using a spirit level on the cills this required a bit of extra work.

I managed to drain 8.5 litres and 8.75 litres of fluid respectively from both gearboxes. My method was to remove the valve body and leave the gearbox to drain overnight. I took a lot of trouble to ensure I collected and measured all the fluid. I believe the capacity is 10.5 litres but opinions and data varies. I purchased in total for both boxes 19 litres of fluid. I still have .5 litre left. Standard refill kits come with 6 litres of fluid in the UK.

I used only genuine ZF filters seals and lifeguard 6 fluid. Personally I think it’s false economy to use anything other than OEM specs. I know opinions vary on this but having investigated millions of pounds (yes really millions of UK pounds) of damage caused when incorrect lubricants are used I cannot bring myself to do it personally.

The bridge seals supplied from ZF did not fit. After consulting ZF technical they confirmed there are two types of bridges seal later seals have additional tangs on them. ZF advise for early boxes you have to saw off the tangs and reshape the seals to fit. I do not recall this being mentioned in any data I have or have seen. I often wonder if this could have caused problems for others if unaware.

With regard to drive-ability the older box is slightly smoother and is slightly slower to engage reverse. On both boxes you can feel second gear engage particularly when cold. Having read multiple lurch stories I consider this to be a characteristic rather than a defect. Both boxes had the squawk before I changed the fluid. The older gearbox squawked once directly after the fluid change. I have ZF technical data that confirms you need to drive 20 miles before they consider the fluid will get fully around the box (yes I am trying to work that out as well) it states the squawk will diminish as mine did.

I do not believe the friction additive is required if you service the box. Personally I think it was a palliative to get cars past their warranty period.
Please respect I am sharing my opinions and experience I may not be right.
Hope this of interest.
Kind rgds
Gas turbine

 

The argument here why some of us have used "other" fluids is that ZF licensed the design of this 6HP26 to Ford (6R60), and these transmissions come with Mercon-SP as the recommended/OEM/Factory fluid. Some of us inferred that Mercon-SP was therefore fine for us too. Your car, your choice of course.

The main reason is cost of course. A transmission drain from the pan is never complete. Maybe the torque converter stays filled. Therefore, some of us perform the drain/refill twice to further dilute the old fluid. This is much easier to stomach with Mercon-SP ($6/qt?) than with LifeGuard6 ($20/qt?).

 

Mercon SP ATF has been proving itself in these ZF 6HP26 units for more than a decade now. I ran it in my previous 2005 S-Type, I run it in my wife's 2006 XK8, and I see absolutely no reason to go back to Lifeguard 6. I would just be throwing money away by doing so....

 

Aside from the red dye added at Ford's request, Mercon SP is essentially chemically identical to Lifeguard 6. Mercon SP is manufactured by Shell U.S.A. and Lifeguard 6 is manufactured by Royal Dutch Shell. Both are also essentially chemically identical to Shell Spirax S4 ATF MSP. Here are the reports received by bimmerfest forum member fun2drive in response to his submission of samples of LG6 and MSP to Blackstone Laboratories:




When you drain the 6HP you will get only 4 or 5 liters of fluid. The remaining 4.5 to 5.05 liters of fluid remain in the torque converter, valve body and other passages. If you drop the pan and valve body (to replace the Mechatronic seals), you'll get 7 liters or more to drain, depending on how long you wait. Published capacity for the normally-aspirated models is 9.5 liters / 10 quarts, and for the supercharged models is 10.05 liters / 10.6 quarts

Doing a proper fluid flush to replace all of the fluid is not too difficult with some inexpensive parts from the hardware store:

ZF 6HP26 / 28 Transmission Fluid Flush DIY

Regarding the adaptation period that fmertz described, my understanding is that the Mechatronic can continually adapt over time to compensate for different driving styles, changing fluid characteristics, and normal wear of the transmission internal components. If anyone has a document from ZF that describes a "one and done" adaptation process, I would love to have a copy.

I am attaching a document from the California Transmission Supply Co., an authorized ZF dealer, that illustrates the different bridge seals depending on the version of the 6HP.

Cheers,

Don

 

Don and All
Thanks for the additional information.
I did not intend to infer that the use of lifeguard 6 was obligatory merely that it was my choice.
Have to apologise to you all but for this comment but CTSC insist on the use of lifeguard 6 when installing their rebuilt mechatronic units. They appear a trusted source of ZF information.
Happy motoring
Kind rgds
Gas turbine

 

No apology necessary. We all have our preferences. Mercon SP is the preference of quite a few of us....

 

I understand Klaus at CTSC selling Lifeguard 6 as part of his ZF 6HP26 refurbishment kit (I purchased one of those kits in the summer of 2013 to do a pan drop and sleeve change on my wife's 2006 XK8). He worked for ZF for quite a few years prior to starting CTSC....