Well forgive me for not being psychic and knowing which Hang Over you've got, at the beginning there were a lot of posts from fellow tractor drivers

Anyway what ever the manufacturers say is the correct service interval, I would half it to be safe. Land Rover say its a sealed for life box in the brochure, 75k in the service manual, and we all know that if it hasn't been done by 40k, you might as well not bother changing oil or flushing, save the money cause you's gonna need it
In fact the only flushing that should done on a gearbox thats done OVER 40k is your dosh down the pan
Don't believe the experts, when it comes to gearbox services, they just want to sell you a new one at £8k, blow a few quid and get in there early  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

I have flushed boxes as low as 50k, and as high as 120k, with no issues. But the cars had no issues to begin with, other than 1 car, it was all preventative maintenance

The LR interval is 150k. If the oil is left this long, the gearbox will likely be
Hence ZF's recommendation of a full flush every 75k

If the early 5 speed boxes are not at least drained and filled every 30k, they will have issues too

What evidence is there that by 40k if the gearbox oil hasn't been changed the gearbox is on it's way out?
Having taken a filter apart from a GM box at 70k to see what was in it and found nothing I have to question the 40k figure.
As far as I'm aware the primary initial cause of GM gearboxes failing is the failure of the torque convertor and the subsequent dumping of aluminium and friction plate particles into the circulated oil. Most of the larger particles will be collected in filter but unfortunately the troublesome finer ones will simply circulate causing premature wear in the gearbox and subsequent failure. I would be inclined to be more concerned about the condition of my torque convertor initially than the gearbox.
As to the gearbox filter blocking, no chance, the filter media area relative to the oil flow is very large.
As well as the torque convertor my only other concern initially would be the condition internally of the oil cooler. The oil-ways do appear to have a reputation for becoming restricted due to debris thereby reducing oil flow and thus causing over-heating of the oil.
I would seriously look to having the oil cooler replaced as a precaution if you intend to keep a car for an extended time with subsequent high mileage.
Just one observation, do all megaflush companies use hot oil in the process or simply room temperature oil?

I run the car until the oil is up to 35 degrees, carry out the flush, disconnect the machine, start the car and top up, then let the car warm up to 35 degrees again, and recheck. As per the ZF instructions

miggit wrote:

we all know that if it hasn't been done by 40k, you might as well not bother changing oil or flushing, save the money cause you's gonna need it
In fact the only flushing that should done on a gearbox thats done OVER 40k is your dosh down the pan

At 100k, you should be fine with just a flush.

Worst case, fit a new filter, as they are very easy to fit in the FF

nicedayforit, there is no set rule as to when to change the oil in your box, My car managed 102k and was still driving, BUT, I'd got those rumbling vibrations, from the rear end between 30 - 50. This is a very good sign that it's all going to go Pete Tong very soon
As we benefit from the GM cheese box, we can just change the oil and filter on a regular basis and cheat the death of a thousand particles, and with careful buying, for little dosh
The problem is not the torque converter, but the torque converter clutch. At lower speeds, 30 - 50, this slips at around 5% to stop the awful vibrations caused by the torque. Hence the term Torque Vibration. Now if you go back to the days before you had a FFRR, and remember the last manual car you drove, how many miles do think you would get riding the clutch all the time? Not many, so the FFRR does rather well, but all this slipping produces clutch powder, and as the clutch is contained in the converter, it's washed out in to the oil system. And that is the start of the down hill slope.
Your filters look clean because the holes are much larger than a standard Automatic filter, which allows all the small stuff to go around and around grinding the gearbox in to the afterlife.
What I was suggesting earlier, was that power flushing was not totally necessary for the GM box because if you regularly change the oil and filter it will all be clean. If you only change half the oil every time, the box will get a complete change in 2 goes, yes I know that this is not correct totally but you get the idea. Modern oils have lots of cleaning additives in them to stop the buildup of muck, but changing half the oil at 24K your boosting the cleaning properties by half at a quarter of the recommended mileage. So the ways will not get blocked and all will still work fine.
It will not make your gearbox last forever, as it contains multiple slipping clutches, and the smoother the gear change the more the clutches slip, so it will wear out at some point. It will however help to get the most out of the box, before the inevitable eventually happens. £226 for 4 oil and filter changes at 24k will see your box into mega mileages. When my box went for a rebuild they were amazed at a 102k mileage, saying that 80k was classed as high. Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

Last edited by miggit on 1st Dec 2014 10:35pm. Edited 1 time in total

I have recently had my gearbox serviced (full flush) at ZF in Dortmund at 100k miles. As far as I know, looking through the documentation that came with the car, this is the first time the oil has been changed.

Their recommendation was to service the gearbox every 120k kilometres. They did say, however, that my gearbox had no problems and was in good condition, so I guess one can't generalise too much.

But, you do have a 6 speed box not a 5 speed which is more problematic sir...

It's really annoying (to me) that auto boxes don't nowadays have drain screw in the torque converter. I have seen a few real old cars With them. And on an old rover I had, I actually drilled a small 3/16 hole and drained it, and welded up the hole! This would give the gearbox a better chance to dump it's 'filth' out in one sitting.
My cars' previous owner had issues with cooling pipes internally collapsing and blocking, found this out after he replaced box! So I have a full recon box and pipes and cooler. (Part or my buyers wish list) Im at about 20k on new box, it will get a semi-flush in 10k.

Hi Craig, I accept that but the thread doesn't really distinguish enough and for non-experts like me, it is confusing and worrying when one reads some of the views and stories. I'm not sure it helps if we end up believing one might as well not bother as it's already probably too late.

Reading similar threads certainly encouraged me to have mine done although I was very concerned about the quality of the services being carried out and the potential for more damage being caused by having it done rather than not. That is one of the reasons why I chose to have it done by ZF themselves.

I agree... Lots of expert advice............... given by non experts me finks sir...

I have taken steps to highlight GM in the above post so as not to confuse anyone, and for those of you who are still a bit foggy, if you pay more than £300 per annum road fun licence, or whatever they are calling roadtax this week, the chances are you have a ZF box. Which is stronger that the GM but will need to be power flushed at the point of oil change
Sorry you can't have reliability and low running costs, it just wouldn't be cricket  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

Cam-Tech-Craig wrote:

I agree... Lots of expert advice............... given by non experts me finks sir...

For clarity Craig, who would you be referring too?