[Jackofallgrades]

I’m taking my 340i F31 to Foxtails near Faringdon, who have a good reputation with BMW work and have been recommended to me by friends. I asked for a transmission fluid service because the car is up to 75k miles now, and they recommended a full flush (ie over 8L of oil) and a chemical cleaning of the pan filter. This is at odds with what I was expecting and had seen online, which was 1-1.2L of oil with a pan change. They explained that as long as there hasn’t been any mechanical wear, or metal filings found in the filter, cleaning them and refitting is perfectly fine. I’m hesitant to say they’re wrong based on my internet searching, but have seen many people saying that a full fluid flush is not a good idea. Who’s right? Help!!

For context my driving has been largely motorway miles, with some day trips into town a couple of times a week, but much of the mileage is easy on the trans.

[Watsey]

ZF specifically advises against fluid flushes - I know, because I discussed it with ZF Technical personally.

The torque converter holds a significant amount of fluid, therefore, the fluid needs to be changed 2-3 times (with the car driven between each change) to make sure that as much of the old fluid is diluted away as possible.

The pan should always be replaced when the fluid is changed.

[danb1979]

As above; it just needs to be a fluid change & new filter

No flushing needed/required

[Jackofallgrades]

Originally Posted by Watsey

ZF specifically advises against fluid flushes - I know, because I discussed it with ZF Technical personally.

The torque converter holds a significant amount of fluid, therefore, the fluid needs to be changed 2-3 times (with the car driven between each change) to make sure that as much of the old fluid is diluted away as possible.

The pan should always be replaced when the fluid is changed.

When you describe the process to fully change the fluid in the torque converter, are you saying it’s more labour intensive than is worthwhile? Or is it actively detrimental?

[Watsey]

Originally Posted by Jackofallgrades

When you describe the process to fully change the fluid in the torque converter, are you saying it’s more labour intensive than is worthwhile? Or is it actively detrimental?

Using fresh/clean fluid/oil in something mechanical can ‘never’ be detrimental.

As for whether the labour / effort / cost is worth it, that’s subjective but in my mind it’s a clear yes.

Never trust BMW’s Sealed For Life” BS. ZF recommends fluid changes in these units at 60K mile intervals.

[TurboWeasel]

It sounds like they are more used to working with older traditional slush boxes. The ZF8 was designed to be low maintenance and easy to service, so literally all they need to do is follow the instructions included in the ZF service kit and they can't go wrong.

[TiredGeek]

Tbh I wouldn't go near them if they say clean the filter. It's a one time use and a new one comes with oil as a kit. Find someone else to work on your expensive gearbox.

[YODI]

If it helps I had mine done on Saturday, using genuine ZF filter/sump with 5L of genuine ZF oil for £152.

There was nothing wrong with the car or how it drove but after having F series cars on and off for ten years and having never serviced a ZF box before I regret not doing it to every car, the car drives so differently now it has become by far my most favourite 'mod'

.
.

[GOF_430d]

Originally Posted by YODI

If it helps I had mine done on Saturday, using genuine ZF filter/sump with 5L of genuine ZF oil for £152.

There was nothing wrong with the car or how it drove but after having F series cars on and off for ten years and having never serviced a ZF box before I regret not doing it to every car, the car drives so differently now it has become by far my most favourite 'mod'

.
.

Yodi, I see that you're in North London, so can you tell where you got the gearbox oil replaced? My car has just clicked over to 100,000miles without a gearbox oil change, so whilst the dealer doesn't offer an oil change, I think it might be a good idea - not that I'm having any issues with the gear changes.

[YODI]

Originally Posted by GOF_430d

Yodi, I see that you're in North London, so can you tell where you got the gearbox oil replaced? My car has just clicked over to 100,000miles without a gearbox oil change, so whilst the dealer doesn't offer an oil change, I think it might be a good idea - not that I'm having any issues with the gear changes.

I wasn't either, but the difference is huge and not placebo.

A good friend of mine is a mechanic at a Garage in East Barnet, he will look after you if you would like to get it done.

[GOF_430d]

Originally Posted by YODI

I wasn't either, but the difference is huge and not placebo.

A good friend of mine is a mechanic at a Garage in East Barnet, he will look after you if you would like to get it done.

Yodi, if you can give me your friends details, I'll give them a call, though East Barnet from where I am in Harrow is about 40minutes and my car is going in to the dealer next week for a service and I will ask them for a cost.