Transmission Fluid Replacement and Transmission Oil Pan

[LazarusTheGrenny]

Starting a transmission fluid change discussion here as several of us have been discussing which pan kit part numbers are appropriate (and potentially an OEM upgrade from the plastic, if available)

@scottg @Krabby and I have had a recent back and forth on discovering the specifics of self-servicing the Grenadier's version of the ZF 8HP. Will port that discussion over in subsequent posts.

 

[Kevin Mokracek]

I just watched a Grenadier service video and the mechanic said all fluids can be changed by the owner but he does not recommend changing the transmission fluid or filter pan, he said have the dealer do that at the 84k mile service. He said it can really jack up the transmission for some reason that he didn't get into.

 

[LazarusTheGrenny]

From @scottg :

Start of Quote:
Before you take your Grenadier's pan off, confirm the new aluminum pan has the 2nd transmission fluid uptake port. Most ZF pans have one large uptake port as part of the filter, Grenadier's use a ZF pan with a second, smaller uptake port similar or identical to the BMW G20/G21s (this pan's setup is for BMW "mild hybrids") if I recall correctly, also part of the filter. The attached picture shows a Grenadier's ZF pan with the second port at the top left. I'll post more when I have time and have better understanding about what the 2nd port does -- it's either there because we have the engine stop/start feature and this 2nd port is to help keep the ZF ready to go in those cases and/or some other reason(s). I haven't found a metal / aluminum ZF pan that has a filter with this 2nd port, and I'm not sure if I can grab the filter with the 2nd port and retrofit to an aluminum pan without the backing mount behind that 2nd port on the pan's floor. If anyone has done this, please post.
/end quote

 

[LazarusTheGrenny]

@Krabby suggested:
"Could the second uptake be to prevent fluid starvation when the trucks are at extreme angles? Off camber or steep in/declines?"

---

My input from that thread:

@scottg great catch here, thank you for posting and sharing this photo.

Interesting development. The pans that I got do not feature that aft pickup. That’s quite curious. The pans/filter’s that I received from FCP Euro are OE ZF and Genuine BMW but do not feature this second fluid pickup. Doesn’t seem like any aftermarket option has one either and I would steer clear of those anyhow. Nor do the 8-speed Jeep Wrangler steel pans.

I was just about to do this service within the hour and now I will refrain for further research & need to source a different OE pan with this fluid pickup configuration, otherwise there certainly could be a pressure variance that the transmission won’t like.

Let me grab those part numbers that may no longer be applicable and some photos of the pans, gaskets and filters.

Edit: Part Numbers for the two aluminum ZF/BMW (same supplier) pictured below:

• M3/M4 pan for ZF 8HP: 24119504520 (Link to FCPEuro product page)
• X3M/X5M pan for ZF 8HP: 24119503407 (Link)

*Important NOTE: ^these may not be compatible with the Grenadier's specific 8HP configuration, and/or with the Grenadier's frame cossmember & aft transmission mount, and may interfere with tool access for rear pan bolts.

I think both you and @Krabby are likely some version of correct: perhaps for start stop (although other models have had this for at least a decade) but certainly for high pitch and roll angles (off camber), it’s a bit odd I would expect there to be enough fluid in the sump given depth of the pan and fluid volume. Hard to know without reviewing any engineering data.

Re: mild hybrid setups: I wonder if the newest gen X3M 8HP would have this filter setup with an aluminum pan/deep fin design.

We likely need to start a separate thread for the topic of transmission fluid changes and pans.

@scottg do you happen to know the part number for your Grenny pan you pulled off?

 

[LazarusTheGrenny]

I just watched a Grenadier service video and the mechanic said all fluids can be changed by the owner but he does not recommend changing the transmission fluid or filter pan, he said have the dealer do that at the 84k mile service. He said it can really jack up the transmission for some reason that he didn't get into.

Hey @Kevin Mokracek, I just watched that video as well!

Great brief from Warner Ineos (powerhouse dealer in North America) and recommended watching, especially on the differential "dipstick" tid bit. Much of this info is being collated by @Rok_Dr from his own and other sources which is excellent and can be found on the forums.

The essential theme to what Todd was speaking to is well known with automatic transmissions. In that, as the transmission's clutch packs and associated mating surfaces wear, the fluid retains much of that foreign object debris (FOD) in suspension and that acts as a friction modifier to allow the transmission to not slip when shifting or transferring torque. Typically this is more of a concern for high mileage vehicles which have never had the automatic serviced and then when the fluid is changed, the transmission performs poorly. The better approach is to service appropriately and avoid the roulette of never changing the fluid, until it's too late. Can also be an issue with some flushing services that evacuate too much of the fluid from the internals. There's certainly additional nuance that I'm not covering, but in essence we should be servicing the transmission with intention.

---

This thread is to discuss the applicable transmission pans and the procedures for drain & fill, as it most certainly can be done and ZF (supplier of our lovely 8-speed 8HP series transmission) recommend much shorter service intervals. The servicing isn't mind boggling, just requires attention to detail (pan, filter, fluid, tools) and conditions (mainly transmission temperature window for proper filling), and thankfully we have a temperature read out in our onboard "Offroad - Temperatures" menu right on the dash! So no diagnostic tooling required for the broad temp range required to fill the transmission properly.

Drain and fill video here (among many other BMW DIY service videos for the B58 engine): FCPEuro ZF 8HP Transmission Fluid Change

NOTE: I recommend that folks certainly go to the dealer or qualified shop to have any maintenance that's out of capabilities or comfortability performed there. That said I've had 'qualified' places not perform work correctly, including dealers (Ineos dealers included) and had to rectify their work after careful post inspection. As well, warranties may be affected by DIY maintenance particularly not having proper records or using improper parts/fluids/etc. so at one's own risk there.

---

Many are also interested in swapping to an aluminum pan from the OE plastic for impact, servicing, and thermal reasons. And there are many vehicles which use variants of this transmission which have aluminum, deep finned pans that are factory/OEM/genuine parts from ZF, BMW and possibly some other OE catalogues. The critical part here is that @scottg has identified that we have a different oil pickup configuration.

So the general hope of this thread is to identify the right parts and any procedural learnings to be able to service this transmission by DIYer's who want to do it and/or perform an OE like upgrade at the same time.

 

[LazarusTheGrenny]

@scottg do you happen to know the part number for your Grenny pan you pulled off your truck?

 

[Stu_Barnes]

I have the zf fluid change procedure somewhere, I’ll put it in the resources section. The main thing I remember from the session I had with them was use the correct lifeguard fluid, change the pan and make sure you get the thermostat open when recharging. It’s a drain, change pan, fill, run, top up process if memory serves.

If you’re doing it outside in winter then put the lifeguard fluid by the radiator to speed up the warming through when running.

 

[LazarusTheGrenny]

Makes sense! Thanks @Stu_Barnes !

This is the same procedure as in the FCPEuro videos which are quite detailed.

 

[LazarusTheGrenny]

Mainly need the part number for the pan/filter.

And the ZF Lifeguard 8 is the correct fluid. I bought 15L to do the first change just to be on the safe side. @Rok_Dr lists 10.6L+ I believe in his fluids table.

 

[C-Mack]

Modern ZF Transmission refills are certainly a doable procedure for the DIY mechanic but you have to be meticulous and follow the steps exactly paying particular attention to the required temperature ranges. Likewise, it pays to make sure the vehicle is up on a perfectly level lift if possible. Driveways and garage floors have slopes for water drainage and can easily throw levels off slightly especially for diffs when one end of the vehicle can read higher and the other lower.

At times I’ve had to raise one end of a vehicle in order to level it off so I could get accurate readings. My garage floor slopes down approx 3” from the back to the main garage door so when servicing my old Range Rover rear differential for example, I can only get just over 1 quart in before it starts to spill out the fill plug. Leaving it that way it’s under filled so in some cases you may need to level the vehicle up first.

 

[Stu_Barnes]

Makes sense! Thanks @Stu_Barnes !

This is the same procedure as in the FCPEuro videos which are quite detailed.

Here is the link to the ZF instructions.

How to Change the Transmission Oil on a Passenger Car

ZF Aftermarket provides technical tips for mechanics on a wide variety of products like brakes, clutches, suspensions and steering components. These tips are our guide when it comes to inspections, replacements and service in the workshop.

aftermarket.zf.com

 

[Logsplitter]

I’ll be leaving ZF transmission oil changes to a reputable garage myself.

 

[LazarusTheGrenny]

Here is the link to the ZF instructions.

How to Change the Transmission Oil on a Passenger Car

ZF Aftermarket provides technical tips for mechanics on a wide variety of products like brakes, clutches, suspensions and steering components. These tips are our guide when it comes to inspections, replacements and service in the workshop.

aftermarket.zf.com

Thanks Stu! These instructions and the FCPEuro videos (linked in an earlier post) - with attention to vehicle being level - close the loop on procedure.

The FCP Euro team also call out filling tools and the like which are quite useful.

 

[LazarusTheGrenny]

@scottg and co:

Did a little parts digging this morning and found the pan that reflects what you pulled out of your Grenadier when you dropped the plastic pan. As you alluded to: looks just like the BMW X3 M40i (at least circa 2023 MY). Quite a pricey bit of kit at ~$500. I'm sure there's a ZF version that drops the "genuine" markup.

Genuine BMW: BMW X3 M40i Transmission Pan - BMW Genuine OE - PN: 24118743462
ZF equivalent (currently backordered): X3 M40i Transmission fluid change kit/pan - ZF - PN: 24118743462KT1 (this is substantially cheaper as the price in the link includes ZF Lifeguard 8 fluid as well)

^this is an unconfirmed fitment for the pan on our Grenadiers/Quartermasters

Scott, were you able to get a PN off your pan? That might allow us to cross-ref. Thanks!

 

[scottg]

I haven't pulled my transmission pan off yet. I asked one of the makers of an aluminum pan (PPE) if theirs would fit, and they sent me the picture I shared with you of a pan someone else had removed from their Grenadier to replace it with PPE's aluminum pan, and they couldn't when they found that secondary port. I've attach a picture of my pan's part number and the PPE pan and the Grenadier pan pics side by side, that PPE sent me.

@LazarusTheGrenny : can you take some pictures of the inside of your aluminum pan? Would be great if someone could use a lidar / laser device to get 3D and measurements of the inside dimensions of that pan and the Grenadier's pan, see how they compare.

What's needed for an aluminum pan is for it to be milled with the backing support for the secondary port, and then to get the filter that has the secondary port built in. I'm not sure an existing aluminum pan can be modified for this safely, after it's been milled. Nor do I know if the filter with the 2nd port can be removed from a plastic pan and used in an aluminum pan. I guess I could buy the INEOS pan, the BMW pan, several versions of the aluminum pans, and compare, but would need to set up a GoFundMe page to cover the costs.

I'm waiting to be given access to the online Grenadier manuals so I can review these parts and part numbers, and pictures -- I attached the information I received from MileOne INEOS.

I've also attached a PDF of what ChatGPT could find, starting with my INEOS part number. Seems there may be several BMW part numbers that would work on our ZFs, but I don't know how to confirm that.

https://www.ecstuning.com/b-vaico-parts/bmw-oil-sump-automatic-transmission/24118743438~vai/

I think the secondary port is for the ZF to maintain pressure via an electric pump during the engine stop/start cycles, but can't confirm that either.

Ideally one or more aluminum pan makers could change their pan designs to have the backing support for the 2nd port -- the ZF pans that can support the 2nd port are compatible with filters that don't have the 2nd port, as I've seen pans for sale that have the backing support with the single port filter.

/s.

 

[LazarusTheGrenny]

Copy all @scottg. appreciate all the insight and detail here along with the legwork with PPE!

I just sent my pans back to FCPEuro to get the $900 back and pivot to the correct part. So I’m without pans but I took photos of them.

This is a solid project to undertake and the BMW pan I linked above is likely our option, for now, priced right at the GRA price point.

I’d be interested to see if the later MY25 and MY26+ M SUV’s will have aluminum pans with this second pickup. That would be my ideal outcome.

An aftermarket version could be solid, but I’d like to see actual internal fins to the pan as well to create better heat transfer characteristics via thermal bridging effects vs. the smooth sand cast finish I’ve seen. This would require more intensive casting tools or a fully milled component (costing big !).

Might be best to maintain with OE Plastic for now and keep the skid plates on!

Let’s chat about next steps, feel free to DM. I’ll share more photos of the BMW M- pans

 

[LazarusTheGrenny]

This is a really solid look at transmission oil pan design from an aftermarket perspective (Banks Power/Gale Banks Engineering), good overview of design, manufacturing, temperatures, etc.

Now it's not directly applicable to the Grenadier, it's analogous to what we might want to look towards:

View: https://www.youtube.com/watch?v=BhsGxgh3OYY

 

[scottg]

This is a really solid look at transmission oil pan design from an aftermarket perspective (Banks Power/Gale Banks Engineering), good overview of design, manufacturing, temperatures, etc.

Now it's not directly applicable to the Grenadier, it's analogous to what we might want to look towards:

View: https://www.youtube.com/watch?v=BhsGxgh3OYY

Great video, and apologies for not DMing you earlier on Grenadier pans and what's next to get an aluminum pan that will work with Grenadiers.

I've been reading BMW Technical training manuals, and I've confirmed that Grenadiers require the 2 pickup port transmission sump pans because of engine start/stop. Mild hybrids also require the 2nd pickup port pans (or rather, filters) even without stop/start for the same reason: the ZF transmission loses crankshaft-driven pumping in both cases, and in both cases, the transmission needs to maintain pressure via an electric pump using that second, smaller uptake port, so it can immediately re-engage when the engine restarts and when the mild hybrid needs the engine back into the mix. A vehicle with both the start/stop function and that is a mild hybrid where the engine will disconnect from the transmission when coasting would need the same obviously, but doesn't need 'more' pressure because there are two methods being employed to reduce emissions, the same works with either or both methods in same vehicle.

(I think the mild hybrid will improve engine and maybe transmission longevity, but the start/stop destroys it. I have my start/stop "turned off".)

I love that the Banks video has the transmission filter on the outside. ZF transmissions have the filters on the inside, and that's where the main uptake port and in cases where it's need, the smaller 2nd uptake port are built into. To make a pan that has the filter on the outside only, some design would need to force transmission fluid through the external filter, and there would have to be the main and 2nd smaller uptake ports replicated somehow where the fluid would be picked up, that isn't part of the filter anymore. But ... having the filter on the outside makes it exposed to off-road damage without extra skid plate protection. (Wait, the ZF pans are plastic, so ... oy.)

For now I think we have no options unless we can find an aluminum pan that can support a 2-port uptake filter. We could see if PPE and other makers would mod their pans to support the 2-port filters, which would still be backward compatible with the 1-port filters and ZF trans. Those who really need a good Banks like pan are those who really push up the temps in their ZFs.

Given that aluminum pans aren't available for Grenadiers now (as far as I can tell), my plan is to use a transfer pump to suck out the trans fluid around 10-20k and replace it the same way, through the fill port, without changing the plastic pan or filter. Oh, change the filter! goes the hue and cry! No. The filter is meant to catch large stuff, and replacing trans fluid via the fill port without changing the filter is fine up until the vendor pan and filter change requirement.

There is some information that says you shouldn't change transmission fluid early or a lot, because that has disadvantages, so I need to research that before I do anything with it.

Before anyone says I'm wasting time and money, I know -- I have time and money to waste and if it doesn't harm my Grenadier, and might help increase longevity, that's what I'd like to do.

Happy to hear counterarguments and such, I'm no expert, but the NASA engineer in me says dude, change fluids often

Sand vs casted -- what about 3D printed aluminum pans with fins?

/s.