While the pan and filter are off, replace the pressure regulator valve in the front valve body with the upgraded ZF #1058-327-030 part. Less than $30, and buy new screws with larger heads from ZF at the same time.

 

believe it or not this is not the first time.....i have heard such non-sense....what i do know and as alluded to above, how this is done makes all the difference in the world!

 

i have 11 cars all with auto transmission
i have replaced transmissions in some of them as i put a blower in one and abused others etc.
i now have it figured it out as i verified this in 3 cars including my 1995 xj

at about 90k i replaced the xj fluid with dexron vi as gm claims that dexron vi ought to be used in all cars that specified dexron iii

after a few k miles the transmission started to slam into the higher gera really hard
researched the heck out of everything ( i am a chemical engineer)
to make a long story short
i bought one each of the following:
type f
dexron iii
dexron vi
mercon
mercon v
and i measured the viscosity ( we have a viscometer at work)
of each one
and i found that dexron iii is more viscous than dexron vi ( although the sales specs online do not show it)
so i replaced the trans fluid with dexron iii and noticed an improvement
therefore i replaced the dexron with type f which is the most viscous of the oils above and noticed a marked improvement

then i added a quart of viscosity improver ( lucas) and now the trans shifts just like before i changed the original oil.

by the way i was spurred to do this research before doing the jag, by the fact that i put a high torque trans on my 2004 Lincoln town car that has a supercharger that pulls over 500 lb-ft ( i had blown the trans after installing the blower)
this high torque trans has bigger holes in the valve plate and was slamming into gear really hard.
after the town car i changed the fluid on the jag and on my mark viii

actually on the town car, besides type f i added 2 quarts of lucas

BTW i think i surmise why the car makers went to lower viscosity in trans fluid and motor oils:
IN ORDER TO CLAIM A HIGHER GAS MILEAGE
so it is a government imposed f** up
something like the hyper-eutectic pistons

 

Same deal with the low viscosity oils.

 

I shall simply say that I have been advised by a Jag-certified (as in works for a dealership) tech not to change the transmission fluid on my car [it has 152K, almost 153K].

It is clear that opinions on this vary, sharply, and virtually all are informed by "what my gut" says rather than anything either the car manufacturer or the transmission manufacturer advise.

I have always believed that "you don't mess with a functioning system" and that following the manufacturer's advice (unless there's a radical technology change, e.g., extended life coolants) is the best route when it remains cost effective and practical.

I will share the "central point":

In a discussion with a ZF tech guy, the idea of 5HP24 and 6HP26 fluid changes or recommendations came up; and what he had to say made sense.

We call them 'fill for life' because of two things. First, fluid technology has come a long way, these are either semi-synthetic [5HP] or full synthetic [6HP], the fluid DOES NOT break down or oxidize like petroleum fluids of the past. Second, these are 'adaptive' transmissions, meaning they adapt or takeup for wear of internal parts and friction discs, etc. We all know the friction discs in there wear over time. That friction material doesn't disappear into oblivion, it becomes suspended in the fluid and keeps going 'round and 'round. That means that friction material still has a roll to play in those clutch packs, and the TCM adapts accordingly. So he asks me, "Ever heard a guy complain he did all the right things, including change his trans fluid, and still his trans 'failed'?? It's likely because he threw out all that friction material [the part in the fluid] right out with the bathwater." Consequently, the clutch packs no longer worked the way they did before, and the trans slipped or shifted badly.

 

Jaydog, (and everyone else) keep in mind that no matter what you do to the fluid, the 5HP24 will probably fail around the mileage you've got anyway. Unless you have confirmation that is has been repaired already, odds are the the A drum or the bearing between the drums will fail.

Just don't blame that on the fluid change! If it was me, I'd go the simplest and cheapest route, drop the pan, change the filter and put new fluid in.

Like I said, odds are that it's going to have to come out for repairs soon anyway. I'm not trying to be pessimistic, but these units have a service life of around a 100,000 miles or so, then they need work.

I can remember when it was a minor miracle for a car to be still on the road after 100,000, but now people bitch when the transmission doesn't last twice that long!

 

At 109k I drained and refilled mine. Drive 1000 miles and drained installed new filter and refilled. Have had no problems. It is utter bullshit to assume that fluid is forever!!

 

The most important points are to use the correct oil, and change the filter.
Esso no longer make LT71141.
Use castrol transmax z or
mercon v
pentosin
mobil 1 atf
or similar
do not use dexron, it does not have the same properties as LT 71141
Make sure that the shop knows the correct way to fill the trans, as they do not have a dipstick; fluid should just run out of filler with trans at 45-50c.
ZF now recommend changing fluid every 60,000 miles.

 

new is better than old.period. I changed my XJR tran-fluid(benz made tranny) . I could tell the instant difference.

 

What I find amazing is that people still want to keep to maintenance schedules that manufacturers spent years and years of R&D on extending to as many, "you don't have to touch it, ever," intervals as they could.

I've got a GMC 2500HD truck with 269K on it that has never had a transmission fluid change and still runs like a top. The Jag has 152K with what I believe is the original transmission fluid. (Also, I'm now wondering if the "GEARBOX FAULT" and several other messages I've received over the last six months were due to a dying battery. Time will tell, but so far nothing, not even the classic "BULB FAIL REAR" since the new battery is in.)

I'm not telling anyone what they should or shouldn't do, that's up to each owner. However, things like oil changes every 3K miles, coolant flush-n-fills every two years, and others are truly a waste of time and money. Having said that, even I change my oil every 6K miles, rather than the 10K (if memory serves) that Jag recommends. That's due to my own age and history with various cars, not anything remotely "rational." In general, though, following the manufacturer's recommended maintenance plan will not "steer you wrong."

 

There are plenty of stories where a trans has failed soon after a long overdue fluid service.
The truth is they were on the way out anyway. Fresh lubricant will never harm a transmission. There is some truth in that circulating debris in the oil provides enough friction for worn clutches to grab. This same debris is also destroying everything NOT supposed to have friction.
Change the fluid and hold your breath, after 128k and no service it won't be pretty.

 

"Lifetime fill" on transmissions equates to the lifetime of the oil. Some like yours last a very long time. I just spoke with a BMW owner who went 302k till it died on what is believed the original fill. Same ZF trans as our cars.
This is extraordinary and not typical, many, I'll say most, die way sooner.
Has anyone noticed the coincidence that these "maintenance" schedules seem concurrent with free maintenance plans offered with new cars? I don't know I'd call that R&D, perhaps marketing. The improvements are in the lubricants, not the machines.

 

Nota bene your last sentence. This is precisely the point. Most of these lubricants now have virtually perpetual service life, and the makers of those lubricants and the manufacturers that use them state this over and over.

New lubricant, that isn't going to work any better than old but perfectly functionally intact lubricant, isn't going to do anything to prevent mechanical failure.

So far, I've had only one car in all my years driving (now approaching 35) that ever had a transmission fail. Virtually none of them ever had fluid changes, and this dates back to Dexron III (and earlier) fluids. As a general rule, both my life experience and observations have indicated that transmission failures are incredibly rare and that most transmissions outlast other parts of the car that die first. Given the number of cars out there, there will certainly be some failures and some maintenance on some cars that occurs. It doesn't seem to be the rule, it seems to be the exception.

The well-known A-drum failure on the ZF5HP series is not due to lubricant failure, but a design flaw. No lubricant could or would prevent the failure mechanism exhibited on these drums. They were underdesigned and suffer from metal fatigue that eventually leads to shearing.

 

While the lubricant may still be fine it becomes contaminated so effectively worthless.
My own ZF quit @ 77k from A drum failure which I agree is not lube related but many others simply wear out.
My own transmissions get serviced regularly. Seeing the debris in the filters, and the magnets with my own eyes is convincing enough for me.
EDIT; I've been inside a few dead transmissions in my days and overhauled a couple myself. I have NEVER seen a worn out one with good fluid in it.
Again, the life of the transmission, barring other events, is determined by the life of the fluid. Fluids are much better but there is no such thing as forever.

 

The first statement is incorrect, at least as far as written documentation from ZF states. These transmissions were designed, from the get go, to expect normal wear material to enter the fluid (and, for the most part, remain suspended in it).

Your second statement quoted above simply reinforces the point I have repeatedly been making.

The last statement, while true if taken to an extreme conclusion, is not true for the functional life of most transmissions and/or cars that house them in current production. These are designed to be "filled for functional life." Barring some accident or unexpected malfunction, the functional life of any car produced since the 1990s is well in excess of 200K miles with proper ongoing maintenance. Transmission fluid changes are not a part of the "proper ongoing maintenance" schedules of many cars produced during this time, specifically including the X308s.

I think I'm done now. This topic appears to be another of those that can never be settled and quoting "chapter and verse" from manufacturers doesn't help to settle anything, it seems.

 

For what it's worth - I have had mixed results with changing transmission fluid in various cars.

Basically here's the argument some old timers, especially in the antique car hobby, state:

The old transmission fluid in the car has lost all of it's detergent capabilities. When you add new fluid, the detergent action can cause particles/gunk to be freed up and either clogs channels or cause friction to the parts.

I have a 1985 Buick Riviera that the transmission filter got clogged (dirt, etc. from 18 years of use) while I was on a trip. Limped back home, changed the filter, fluid and no problems.

I have a 1992 Buick Roadmaster that when I bought it I proactively changed the filter and fluid. Within 400 miles the transmission went. Guy who rebuilt the transmission said the detergent was the culprit. He mentioned a non-detergent transmission fluid (I have never seen - but I have not looked hard). He also talked about changing filter and using OLD trans fluid if it was not burnt.

Along these same lines, I have a 1951 Buick Roadmaster with 30K miles. I use a straight HD 30 oil that is detergent free. Again, was told this by MANY old timers not to risk freeing up gunk.

I am not saying what should be done but just giving my slant.

 

Boys:

I had my fluid done just yesterday on an original '98 (!) tranny with 97K. So, perhaps I'm a test case! I'll let you know. Meanwhile, pray for us sinners now and at the hour of our transmission failure! My mechanic said the oil looked normal, and not overly burnt; and there was little of anything on the magnets. That bodes well for the transmission, but not necessarily for an inherently weak A-drum. I've heard that oftentimes if/when that failure occurs, it can be fixed by installing the new drum plus the updated valve body rather than a full rebuild. Thoughts? Perhaps I'm planning ahead...

Scott

Scott

 

I have mentioned the improved main pressure valve recommended by ZF in this thread and elsewhere, but there appears to be little interest. At least read the article at jagrepair.com. It takes less than 1 hour to install if the pan is off for a filter change and costs about $30 with shipping. I will copy the url below, but it may not open properly.

BMW ZF5HP24.pdf

 

And I'll conclude by reminding everyone that transmission shops do a brisk business of overhauling these "sealed for life" boxes at well under 200k, that nearly every mechanic will service his own transmissions and that a manufacturer's recommendations aren't always in the customer's best interest.
For anyone, including ZF or that crusty old geezer mechanic, to state that old fluid is equal or superior to fresh is idiotic. Also, ONE overheating of the fluid will renders it useless as well.
We could further the debate to the FILTER being the determining factor as it is responsible for capturing the debris. I have personal knowledge of an informal experiment conducted by Mazda personnel in the seventies where engine oil was not changed, only the filter and topping off(rotaries consume oil by design, especially early ones), the test car was wrecked after something like 60k miles so nobody knows how long it could have gone.
I stand by my position that not servicing a sealed for life trans is neglect. Some will get away with it, most not.

 

Different strokes for different folks.

Several mechanics that I use will not change transmission fluid, period, barring some need to take the transmission apart.

Most of the failures in our transmissions are due to part failure, particularly the A-drum, sans any other issues. No number of fluid changes are going to overcome design flaws, and that's clearly what's at play here.

Fluid manufacturers could make a fortune selling the fluid for our transmissions as a regular service item. That they don't go this route says volumes.