[Jonny2400]

Hi Chaps,

Well after 4.5 years am about to tick over to 70k so it’s time to get the gearbox serviced.

I’ve spoke to two mechanics both of which I rate, but they have different views.

One recommends that the ZF service kit is used, which means, opening the gearbox draining out as much oil as possible and replacing the seal, filter and pan, obviously this only replaces about 60% of the oil and 40% of the old oil remains. Cost £600.

The other recommends a ATF flush, using ZF oil and not opening the gearbox and not the service kit as this is the only way to replace 100% of all the old oil with fresh oil. Cost £450 with ZF long life 8 / £300 with Shell ATF.

He also says that there is zero need for ZF oil, it’s not special, it’s made by shell and he’s got BMWs that he works on that are on over 250,000 miles and he’s used shell oil on their ZF gearboxes every 60k never had an issue and am just wasting an extra £150 on ZF oil.

I genuinely don’t know what open to choose, as I see pros & conns for both, I would get the ZF oil either way, as I like to keep things original.

What’s your thoughts?

[admranger]

I don't know why you wouldn't want to replace the filter. Yes, flushing the oil out would be nice, but having a clean filter seems pretty important.

[aerof16]

If you’re worried about it, just do both!

I agree that it isn’t necessary to use ZF gear oil but when it comes with the kit I ordered to do mine, well it just makes life easier.

Where did you come up with the 60/40 numbers?

[Jonny2400]

Originally Posted by aerof16

If you’re worried about it, just do both!

I agree that it isn’t necessary to use ZF gear oil but when it comes with the kit I ordered to do mine, well it just makes life easier.

Where did you come up with the 60/40 numbers?

It’s pretty common statistic, due to the 3.5 litres left in the torque converter after draining, hence the kit comes with just 7 litres and not the 10.5 needed to fill a new dry ZF8HP75.

[aerof16]

Well, like I said, you could do both if you’re really concerned about it. Flush fluid, then drain and drop/replace pan with filter, then refill.

[G30M]

1. use ZF oil. do not use anything else. if the guy says it's from shell that's what he says. not worth the risk for 150 quid seriously!

2. if there is absolutely nothing wrong then you may flush. sometimes if there is loose material from a slightly broken something, that loose material is lodged in a safe spot and won't move unless you flush it. if you flush in that situation the loose material may lodge in a new spot and grind something else and you have bigger problems. so it's a risk. doesn't sound like yours but in very old gears, the gears are held together by an amalgamation of sludge and loose fragments - flushing will be the nail in the coffin for that gearbox.

the best way to change more of the oil is to come back in a year and change the oil again, then you get another 60% of the 40% left. i change mine every 20-30,000 miles for that reason. no flushing.

[Jonny2400]

Originally Posted by g21

1. use ZF oil. do not use anything else. if the guy says it's from shell that's what he says. not worth the risk for 150 quid seriously!

2. if there is absolutely nothing wrong then you may flush. sometimes if there is loose material from a slightly broken something, that loose material is lodged in a safe spot and won't move unless you flush it. if you flush in that situation the loose material may lodge in a new spot and grind something else and you have bigger problems. so it's a risk. doesn't sound like yours but in very old gears, the gears are held together by an amalgamation of sludge and loose fragments - flushing will be the nail in the coffin for that gearbox.

the best way to change more of the oil is to come back in a year and change the oil again, then you get another 60% of the 40% left. i change mine every 20-30,000 miles for that reason. no flushing.

Thanks. Yeah I don’t have any issues with it, feels as smooth as the day I collected it new. Saying that my F10 which I also had from new, gearbox was still smooth when I sold it on at 137k and I never got it serviced.

I think your prob right, I’ll just get the ZF service kit fitted and be done. Probably the lowest risk option.

[srybicki]

Fcpeuro has kits and I have been using liquimoly trans oil they sell with 0 issues.

[WretchedRefuse]

I don't see a kit on FCP Euro for the 2020 M550i. Can anybody point me to that if it exists?

[Hoa]

Transmission pan doesn’t leak as often as valve cover or oil filter housing. It is ok to keep the pan on. ZF transmission are pretty good. Filter is very big so if there are any debris, it will be in there and it won’t cause any issue.

Here is my F10 transmission pan at 281K miles. It did not leak. I cracked the drain bolt when I drain and filled at 273K so I decided to replaced the pan. If it wasn’t for that, I think it should last the “lifetime” of the transmission.

I did not use ZF fluid. I used Pentosin. I’m sure any fluid brand is ok as long as it’s for the ZF transmission.

[srybicki]

If fcpeuro does not have something. Call and more then likely they will add it to the catalog.

[WretchedRefuse]

It took some searching but it looks like this is the one. It's just the pan, filter, and bolts so need to purchase the oil separately. There is no "kit" per se for this model. It's troubling that FCP Euro only lists it as compatible with the M550i through 2016 but here it's specified all the way up through 2022.

Now here's the kicker; the pan specifies using BMW oil #83222289720 which runs $50.38 per liter. FCP Euro lists ZF S67109031201 as a replacement for $15.79 per liter. Needless to say, I grabbed 7 liters of the ZF.

[RRF985]

I found a service kit on FCP’s site that contains everything. I believe this is all that is needed for the trans service. I’ll be doing that in a couple months with my next oil change.

[Jonny2400]

Anyways, got the gearbox serviced, had the full flush and new ZF pan & ZF oil. Total cost including labour was £510.

I’ve done about 6/7000 miles since and zero issues. Did I notice any difference.. umm it maybe shifts fractionally faster, but like I say, fractionally to the point any improvement is almost unnoticeable.

Then, I didn’t have any issues before the service and I’ve now peace of mind.