Hi all, I keep reading conflicting info on how much oil I need to do a change, likely as there’s a few different ways to do it. Most kits come with 7 litres which they say is enough to do a “double flush” which to me means emptying, filling, running the car, emptying and filling again.

others have said 7 litres isn’t enough to do this, or that I could empty, run the car for 30 secs to pump everything out the oil cooler, then refill.

Grateful for any experiences. Thanks.

 

I have been done oilchange for ZF 6HP and 8HP trannys maybe 10-15 times, and dropping the oil/pan and filling up again by correct process descripted on ZF instructions take about 6 liters of oil. (+/- 0.3 l)
You need min 13 liters to do it twise. Doing twise in row is only needed if the box haven´t seen new oil for looong period. Naturally then you like to change the pan(filter) twise as well.
I would drive a some days, maybe a week, between changes to let new filter collect as much friction clutch plates particles from oil as possible before second change.

 

thanks, I should have said it’s the 6hp and it’s 11 years old, 95k and never had it changed. Do you think two changes are warranted please?

does the ZF procedure involve starting the engine to pump it out the cooler? All videos and write ups I’ve seen don’t do this and just do a simple drain and are only putting in around 4 litres before it’s full again. Even when warmed and topped up.

thanks again.

 

For 65k miles i would just prepare for one change and check the condition of oil coming out. If its smels burnt instead just normal bad, i would do second change.
No flushing needed or empty the turbine/cooler by running engine. (running engine without oil inside can damage the oil pump or bearings)
If you purchase ZF 6HP service kit, with oils, pan and screws, it include a good instruction booklet. Or you can watch how to do it from ZF service channel:
I highly recommend the ZF HP6 28 service kit with correct oils. (Lifeguard 6 for 6HP) Its reasonable price, available almost any good parts shop because same tranny are used in Land Rovers, BMW:s, Audis, VW:s, KIA/Hyundai, Ford, Porsche, Aston, GM, Bentley, Maserati ...

 

I always bleed out the fluid through the oil cooler hoses until it runs clean. It's so satisfying to know you aren't leaving any of the old and dirty fluid behind.

For the bleed, I drain the pan through the drain plug, replace the pan/filter, fill it up to the top of the fill plug, remove the return line from the cooler and put an extension hose into an empty gallon plastic jug, run the engine until the jug fills up half way with fluid, and repeat until the fluid runs clean. Then I follow the normal procedure for setting the level. Never had any trouble with any of my several ZF transmission, or any other make of transmission, doing this method.

 

Just did the fluid change on my 2019 XJL. It took 12.5L in total to bleed out all the old fluid by removing the transmission fluid hose from the transmission cooler and running a rubber hose into a catch container.

When I dropped the pan, I got out about 4 liters out. So that means there's more than half of the dirty old fluid still in the transmission. It doesn't make sense to do multiple fluid changes when you can simply bleed out all of the old fluid by removing the transmission cooler line and start to car to bleed out 1 liter at a time. Then, refill that liter through the fill plug and do it again until you get all the old stuff out. It takes about 7 seconds of the engine running for 1 liter to come out, which safely makes sure you won't run the transmission dry.

I removed the transmission line closest to the firewall on the trans cooler because it's the easier one to reach from underneath the car and it flushes out the old fluid in the trans cooler as well.

Here is a pic showing how dirty the fluid was after only 5 years/27K miles. The far right is pure fluid straight from the bottle for comparison. Keep in mind that's only 27K miles of easy driving and the fluid is already that black. Jaguar says the fluid is for life, ZF says it about every 60K miles, but the independent company in the UK that is famous for being the specialist for rebuilding failed ZF transmissions recommends every 30K miles. So I am going to go with 30K miles or less.

My car is shifting just as before as before the change and is good to go for years since I don't do a lot of miles.

Definitely don't do the multiple drain and fill procedure. The multiple drain and fill is just a lot of work to keep a lot of dirty fluid in the transmission.

 

Sorry to offer a contrary opinion, but late model transmission fluid change is a really bad idea.
ZF, the makers of the transmission, say change the fluid every 25000 miles.
Mercedes, BMW, Jaguar, etc. say "Good for the lifetime of the car" (usually gats out of warranty before failure)
Nobody ever changes the fluid that often.
HP5 and later gearboxes are very smart, and edit the conntrol functions based on sampling the qualities in the used fluid.
Changing to new frightens the computer, and the increased solvents in the new fluid rinse all the particulate debris in the unit,
down into the micro passages in the shift control systems.
A fluid change will OFTEN create shifting problems within 5000 miles.
As professionals, we change the filter (sump pan) when requested, only adding enough fluid to make up for losses incurred in the pan change.

Sorry for the bad news, thirty years of experience with this issue says pay attention.

 

Don’t be so sorry.

I just changed my transmission fluid at 27k miles. And I will keep up that interval. So who is nobody?

ZF makes the transmission and they recommend 60k miles. Should we trust your 30 years of experience or ZF engineers?

 

Don´t know where you get this info, but been talking directly to ZF R&D engineers in Germany and they told that no matter what car manufacturer say on their service leaflet, the transmission oil change is mandatory and ZF have even made instructions well available for public for anybody access as well the service kits with filters, oils and screws.
Never seen any ZF model required 25000 miles oilchange, at least one used on JLR vehicles. Typically 50000 to 75000 miles or 8 years.
More info here:
https://aftermarket.zf.com/en/afterm...l-change-kits/
ZF Service have own Youtube channel as well:
Here is their HP6 service video:

Edit: Many person think that electric vehicles are service free, but on these the transmissions need even more care and fluid chances are very important.

 

Again it pays to go right to the source instead of listening to "Armchair Experts" with decades of out of date experience.

Your kidding right?? "Changing to new frightens the computer, and the increased solvents in the new fluid rinse all the particulate debris in the unit"
Can you explain how I am to frighten a computer?

Here is what ZF has to say about fluid changes. And as posted above you simply CAN NOT change the transmission oil too often or too soon!
The document where this came from is attached.




That's pretty black and white from the company that designed and manufactured the transmission.
For us dumb Americans that's 50K-75K miles.
.
.
.

 

I guess my gearbox computers aren't very smart!
When I changed the oil on the 5.0 n/a (HP6) at 52k, it stopped slamming into reverse and the gear changes were noticeably cleaner.
I changed the oil on my wife's F-Pace 3.0 at 56k (HP8) and it stopped 'lurching' from 2nd to 1st as it came to a stop.
I haven't touched the 575 yet.

wombat