For anyone looking to do a fluid service on the ZF 6HP26, after doing a bit of research here, as well as BMW, Range Rover, Hyundai forums, you might find helpful to know that the service can be done at a very reasonable price.

I got the pan, gasket, sleeve, and replacement larger torx oil pan bolts for $70 on ebay. It isn't listed as fitting the X350, but it does just fine:

New 6HP26 Auto Transmission Oil Filter Pan Repair Kit Fit BMW 24117571227 | eBay

Then I ordered the fluid here:

ATF Transmission Fluid Mercon SP, XT-6-QSP, Motorcraft

It comes in a case of 12 quarts and with shipping totals at $80, which gives you enough to do the service, then drive for a month or two, and do a quick drain/fill to maximize the fluid turnover.

I know there has been many debates of Lifeguard 6 versus any alternatives, and I won't rehash all that, but will report to those interested that I found posts on other forums where someone had Lifeguard 6 and Mercon SP sent out for analysis. The variation was no greater than it would be between different production batches of Lifeguard 6 itself, and it meets the Shell M1375.4 spec.

If you only want 6 or 7 qts, you can pick up at O'Reilly for $7.49/qt which makes the service even more reasonable.

If your X350 has more than 80K miles on it, and you haven't done the service, I highly recommend it. Remarkable improvement in drive quality makes up for the kludgy service and fill procedure.

 

I would do a full flush on the spot when switching to another fluid like SP. I did it and I'm very happy with the results, but I don't know how similar the fluids are since the SP is red and I'm not sure how well the add packs mix.

 

AFAIK, a full flush isn't easy or perhaps even possible. By letting mine drain for over 24 hours I was only able to get a little less than 7 liters out, and I believe the units are filled with 10 liters at the factory.

I couldn't find a single incident or report of anyone having any issues or problems using Mercon SP in the ZF 6HP26 across all car forums of models that use the transmission.

 

It shouldn't be a problem, just being overly cautious. When I did the flush I removed the cooler lines since I was repairing them and ran a hose from the pressurized side into a bucket for the fluid to pump into while filling, using the trans pump to evacuate the old fluid by running the engine.

 

Were you able to get out 10 liters?

My understanding was that even using the cooler lines, you'd still have quite a bit in torque converter.

 

Awesome! Gonna order mine today. Thanks!

 

The lines from the cooler come out of the torque converter to cool the fluid after it's been used. Since I was adding as I went to keep the pump from aerating it's hard to say what the exchange was. My cooler line leak was pretty significant and my best guess was that the transmission was 2-3 quarts low and I used a full 11 quarts while flushing and topping off.

 

Is the brand of the pan and other parts on ebay inferior to what others have used on this forum? Just curious if there would be any difference as to quality.

 

As Torrid stated it is perfectly possible to get 10 qts out by undoing the appropriate oil cooler line.
I did this on my Dakota truck several years ago and decided to do the same on my 2005 XJR earlier this year.
When you just drain the pan and refill you are of course diluting the good stuff with the old stuff. Driving around a bit and doing the same you still end up with a high % of the old stuff pumping around.
Having said that many people do exactly that and have not reported any problems but why do that when it is so easy to flush it all in one go.

 

Mac,

Thanks for the great report!

I know I am not alone in my interest in the analysis of Lifeguard 6 and Mercon SP that you mention you found on another forum. I've been hoping a petrochemical engineer would join the Jaguar Forums and be willing to analyze the two fluids with gas chromatography and/or mass spectrometry. It sounds as though someone on another forum has done that. Could you possibly post a link to that information?

Thanks!

Don

 

Goodness Don, I wish I'd thought ahead on that score and bookmarked or noted my research, but I've failed you there.

As a little background, I have been thinking about tackling this job for over a year. When I first read about the procedure and people having trouble with pan bolts stripping and so forth, as well as imagining having to do the whole thing lying on my back, I kept putting it off.

I would however, re-read threads on the subject trying to screw up the courage to tackle it, and started to venture into other models on the forum that used the transmission. Then onto other makes and models that used it as well. Every couple of weeks, I'd hit a forum and do a search, soak up the info or read the debates, and try to separate the wheat from the chafe. Lots of contrary information and opinions out there.

I'd likely still be putting it off until my wife (who drives the car more than I do) mentioned it wasn't acting properly. So I knew it was time to make decisions and jump in.

My apologizes that I didn't have the foresight to note where I'd found the most valuable information. It should have occurred to me, but then I was trying to avoid the job all together, let alone to imagine I'd be posting on it...

 

I found this..Lifeguard6 = Mercon SP?

 

The thing worth noting here is that the fluids aren't the same exact fluid anymore as noted in this thread here that states they are the same color with the same smell. SP is now red and smells like Dex/Merc fluid. It is working flawlessly for me though as it is still intended for the 6HP26 in the Navigator.

 

The bolts actually poke thru the transmission flange at the top. Which is why they can corrode. So if you can spray penetrating oil at the point where they poke thru and leave overnite you have a better chance of getting them out.

I disconnected both cooler lines because it was easier than trying to disconnect just one at the transmission. If you do this be aware that fluid ejects
with some considerable force. I used a plastic lid to deflect the fluid down into a wide container. I would only allow the engine to run 1-2 seconds then top up with new fluid. Its a two person job. I also had to blow the fluid out of the cooler because of disconnecting both tranny cooler lines.

 

I was able to find one of the references to sending out the fluids for analysis:

335 with ZF Auto Transmission Blackstone Results

It's on a BMW forum.

 

Not to play devils advocate... but lets discuss how often will someone replace the fluid?

Let's say that one performs the service every 70k mi? So for an average car (200k mi); it is twice during its life time. Is saving $150-200 each time worth the added risk? I am sorry but if $500 extra over years of ownership is an issue; then, this isn't the correct car for you.

Lastly, I could care less if the pan on ebay fits. The big question is "will it perform as good as OE unit?". I would NEVER put non-ZF pan/seals on my transmission. The risk of failure is too high to save $100.

I am going to do full service on my transmission this week at Edwards transmission for $460 with proper ZF parts & fluid. I am also doing rear differential fluid change for $140. I am @90k miles and those fluid changes will last me a long time.

 

I wouldn't use the non-OEM pan either, but I've never stuck with the same fluid in a transmission, not to mention LG6 is impossible to get in a pinch, it has to be ordered. I had no choice with only super expensive Jaguar fluid or SP from O'Reillys and 1 day to get it repaired and filled. I did not replace the pan at all and cut off the hose sections that were leaking and replaced them with transmission line. After my positive experience I'll just use the SP when I replace the pan and sleeve.

 

Every automotive forum in the world has ongoing debates about OEM parts versus aftermarket, nothing new. Is there a conceivable reason that ZF might charge a premium over equivalents on the market unrelated to performance or quality?

After owning and driving Jaguars for over 30 years, the odds that OEM is guaranteed better quality than all available aftermarket products isn't very high. As often as not, aftermarket products often offer an improvement over the original [like the oil pan torx bolts in this case]. It isn't that I can't afford to pay the difference, it's that I don't need to. Nor should anyone else if there are quality alternatives.

 

I would love to get away from the plastic pan myself. I'm gonna change the fluid out this spring.

 

So who would flush with liquid gold at $26/liter?

Hot tip on the flush ... pull the fuel injection fuse ... then use engine
cranking on the starter to pump the fluid. Much more controllable.

You poor sods with ZF transmissions. The pan/filter alone would pay
for at least 5 full flushes on the Merc transmission using el cheapo
Valvoline Maxlife Dex/Merc. Genuine Merc filter is something under $30.
We might not have a dipstick, but at least we have a fill tube.

Oh yeah ... only six pan bolts and they don't strip out except in
the hands of the extremely ham fisted.

As for $90 differential fluid changes, some can do and others
pay.