I had the atf fluid in my 2006 diesel S-type changed yesterday, and I've had time and mileage to evaluate. This may be of interest/help to readers.

The logic I used was that,
1) My autobox has done 120,000mile.
2) It was not working properly, although the faults were subtle.
3) A recon autobox was going to cost £1,000 plus removing and refitting.
4) An atf change would either, a) make it worse, b) make no difference, c) make it better, for a cost in fluid of £66, labor of £85 +VAT.

So I took a calculated gamble in changing the fluid. I supplied full synthetic which quoted the LT71141 and Dexron VI. This fluid had a nondescript maker on it, but I understand it was really Mobil. Because I had proof (for this autobox) that "Forte" atf additive was obviously beneficial, I also supplied one tube of this.

These effects were noticed during testdrive:--
1) The clutchpack judder between 2nd. and 3rd. had largely gone. This may go altogether with use.
2) The torque coverter clutch hunt had changed: Instead of sounding like someone snoring, it has a lighter sound, and the rpm change has lessened. I think this is how it should be, as according to what I can find out about this autobox, the converter clutch can be in PARTIAL engagement at times, giving a +or- rpm change of 50, which it now seems to be acc. to revcounter.

Probably the biggest, and completely unexpected change, has been in the mpg. figure. From the test-drive, over familiar journeys, I would have been happy with a little over 30mpg. The reading from the car's computer was, wait for it,
43mpg. And this computer is reasonably accurate.

This huge change in mpg leads to logical conclusions.
The old fluid MUST have been wasting a lot of engine power. Energy when downgraded always goes to heat, so the autobox must have been running very hot.
The autobox is working now more or less as it should, even with a fluid not specified by the manufacturer, and same for the additive.
Probably the most serious conclusion is that claims about the autobox being "sealed for life" are not only wrong, but polluting our atmosphere with unnecessary extra emissions.
In my opinion, autoboxes should have fluid changed at 75,000mile for moderate driving, or 50,000mile for enthusiastic driving/trailer-towing.

If any faults show up over time, I shall be honest and report them.
Leedsman.

 

Three questions:

What make and model trans is in your S? ZF?

If a ZF like NA S, is the fluid a match for ZF specs?

How much fluid was changed? A full fluid change is somewhere around 10L.

If less than the 10L, is the fluid you used compatible with the factory fluid that is left?

I know, that was four but the last one just crossed my mind.

 

The 2.7D uses the ZF 6HP26, as do all the auto S-Types after the 2002/3 re-design.

He says that fluid is NOT a match (and he's right, according to ZF/jag).

 

Best wishes with your new fluid continuing to offer improved operation and performance of your ZF. Please keep us posted as you gain more experience with it....

Has your car actually done 120,000 miles or is it 120,000 kilometers? There's a big difference and I just want to be sure we're comparing apples to apples....

I'm also curious as to how much of the original fluid you were able to drain out of the ZF....

And although it's good to hear that your mpg has increased, I'd be surprised if you're truly getting 43 mpg even with a diesel. You may want to calculate a few tanks manually and compare your findings to your computer readouts....

 

Although I am bit sceptical about the fluid change...I do find the mpg findings believable. Watch the video segments from Top Gear when they raced three diesels.
Part 1
http://www.bluemotion.me/economy-rac...p-gear-part-1/
Part 2
http://www.bluemotion.me/economy-rac...p-gear-part-2/
Part 3
http://www.bluemotion.me/economy-rac...p-gear-part-3/

I actually love diesels....I know the power falls off the face of the earth once you leave the power band, but turbo's help...I remember when the euro diesels were here in the 80's and loved them...Then GM tried to convert their gas engines for diesel use...And well, the rest is history..Not to mention that diesels had yet to reach the level of refinement that they have today plus gas got "cheap" here again...

 

It'll be miles - he's in England

The only things wrong with diesels are the smell (horrid), the particulates (life-threatening), the clattery noise (sound deadened quite well on the 2.7D), the risks of total engine failure caused by the now-mandatory particulate filters, the unreliable turbos, phew I better stop.

 

Not a fan, huh? You almost sound like Jeremy Clarkson.....

Actually the BMW and Jaguar diesels are the only ones that he has even remotely sounded positive about that I have heard....

 

Notes re. responder's comments.
Jeremy Clarkson on one of his "Top Gear" shows drove a much bigger Jag with the diesel engine over a distance of several hundred miles, achieving more than 40mpg. He spent some time driving over 85mph.
According to Castrol, atfs with the same specification are both miscible and compatible. I checked my mpg. computer over several weeks using the full tank-full tank method for mpg. assessment. The car's computer I guess is easily within 5%.
My fluid installer filled another diesel S-type autobox the day before mine with Dexron III specification fluid with no problems.
The job wasn't a flushout, the torque converter still had it's old fluid. I would have liked to find a garage with one of those machines that blasts the old fluid out via the cooler lines, but I couldn't. The man did however replace gasket and fluid filter after dropping the sump. The old fluid was blackish but did not smell of burning. It had a kind of 'industrial' odor. I can't say I notice any odor with diesel engines, there is a slight one from the diesel fuel itself when filling. In UK they put a small amount of perfume in the fuel. The old days of black smoke from diesels are long gone. That's because of the high price of diesel. I NEVER see black smoke from diesels as I drive about, not even wagons. In UK, diesel particulate emissions are part of the MOT yearly test, and failures are usually caused by partially blocked injectors.
The car has done 120,000MILES.
The autobox took around 7litres. I think a litre is about the same as a quart.
Hope I've answered all queries.
Leedsman.

 

What have Castrol got to do with it? The ZF fluid is not from them. The fluid you say you've used is a different specification. (I sure hope it works, though, as it's lots cheaper!)

There's a definite smell from diesels as they drive along but maybe you just don't notice it.

There's LOTS of smoke from diesels, especially trucks and buses. The MoT does a VERY crude test akin to useless.

A litre is indeed about a (US) quart.

 

Well, what's good enough for the Ministry of Transport (MOT) -- is good enough for me.
The opinion of a well-respected international maker of atf fluid, "Castrol" -- is also good enough for me. Really, these are non-issues.
I thought it was rather obvious I am carrying out a cost/benefit excercise here, which MAY benefit readers of this forum. But it needs a rational/scientific approach to be effective. I have learned from abt. 45 years of fault-finding and fixing in the electronics business that this is the only way to get good, permanent results. I see all this as 'payback' for me, since contributors to this forum have been so helpful, the whole point of running a forum surely.
Leedsman.

 

Please deal with the issue about Castrol. The oil you've used isn't the same spec as the ZF one, is it?

I've already said I hope it works out so raising payback is irrelevant - it was already clear.

We may as well disagree about MoT and diesel but note that the EU are all the time introducing far stricter standards due e.g. to particulate matter and HC effects on humans (and say explicitly so). The MoT lags years behind, does not test except at most at 2 speeds with car parked, plus existing grossly-polluting vehicles are not required to pass the tighter laws.

 

Hi Jeff,

Those GM diesels were total disasters as I recall. The modern Jaguar diesels that were in the S-Types and in the current models are quite refined though. The 43 mpg Leedsman obtained seems to be in the normal range considering petrol 3.0s get about 30+mpg highway. In the UK diesels make up about 50% or more of the Jaguar market based on what I've read. If they were available here, I would definitely consider getting one.

Mike

 

The 6 Speed ZF transmission has the filter made integral to the pan. The pan is also plastic. You need to replace the entire pan and filter assembly if you want a new filter. So I am a bit confused on how you can replace the filter separately when it's all made as one piece??
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T-bird, my bill says "replace sump gasket and sump tray". I suppose as you say, the filter is part of the 'tray'.
It's "Croft Autos" of www.croftautos.co.uk The owner, Kevin Taylor is most helpful if you care to call him, the number is on website.
Leedsman.