ZF 8 speed fluid change questions.

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Hi
I've read and watched lots about changing the transmission fluid in my 2014 Ram 1500 with the ZF 8 speed but I still have a couple of questions.

Do I drain the fluid when its cool or when its between the 30-50C (86-122F)? One video https://www.youtube.com/watch?v=kXK...Ds9wMi6TZg&start_radio=1&rv=kXKhZievmSI&t=924
said to drain it when its below operating temp but I thought I also read to heat it up first. Does draining it cool keep the fluid out of the tranny cooler so more comes out? Once comment in the video said to drain and then run the engine to get the oil out of the cooler - this sort of sounds reasonable - needed? Dangers?

This video talks about how to make sure you have the tranny full to do the regular fill procedure then drive the vehicle until its hot, let it cool and then do the fill check procedure again. This is to make sure the tranny cooler was full too. Needed?



The last thing I'm questioning is how to do the rev to 2000 part of the fill procedure - is this in park or neutral? Does it matter?

Thanks for the help.
 
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Don't know about the other questions, but I would never start the engine with the pan off/fluid drained, not even to get that last bit of fluid out. Yea, there will be some lube still on the moving parts, but not enough for my tastes.
 

Frznrth

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Does sound like the reward is unlikely worth the risk.

Would it be “worth” doing the whole pan/fluid change driving for a while then changing out just the fluid? It just seems “wrong” to leave all that old fluid in there. Or is the service more about changing the filter?
 
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Having changed the fluid in my 2019 Jeep Wrangler Unlimited 3x thus far, I can help with your questions.

You will need about 5 QTs of ZF Lifeguard 8 or Mopar 8&9 Fluid. The ZF fluid is cheaper and can be found on ebay. My Jeep has a replaceable filter whereas I believe your RAM has a filter that is built into the pan requiring a replacement of the pan.

Here is what you do:

1. Have all of the fluid, filter, and required tools ready at the vehicle. With the vehicle cold, place your drain pan in position and remove the fill plug.

2. Allow the fluid to drain until it stops. If your pan has a built in drain plug (some do and some don't) then remove the drain plug and allow the remainder of the fluid to drain.

3. If the pan does not have a drain plug, then remove all of the bolts except the ones in the 4 corners. Loosen the remainder of the bolts, loosening the ones in the rear a bit more and allow the fluid to drain. When it stops, remove the pan and dump the remainder.

4. If there are removable magnets in the pan, then clean and replace them. Replace the filter (if removable)--snug the filter retention nuts, then back off 1/2 round to allow the filter to move horizontally to align with the filter inlet. Otherwise, install the new pan and tighten to specifications:

Plastic pan = 10nm
Steel pan = 12nm

5. With the engine stopped, fill the transmission until the fluid runs out, then replace the fill plug and snug.

6. Start the engine and allow the transmission to warm to at least 86°F.

7. With your foot on the brake, shift from P to R to N to D to M1 to M2--PAUSING at least 10 seconds at each gear. Do this twice.

8. With the parking brake set and the wheels chocked AND with the engine idling and the transmission between 86°F and 122°F, remove the fill plug again and fill the transmission until it pours out.

IMPORTANT - the vehicle HAS to be idling in park to complete the fill process. IF it is not, then the transmission will be low on fluid.

9. Replace the fill plug. Drive the vehicle for about 5 to 10 miles.

10. With the parking brake set and the wheels chocked AND with the engine idling and the transmission between 86°F and 122°F, remove the fill plug again and fill the transmission until it pours out (it may not require additional fluid--but the drive will purge any remaining air from the new filter and the system--mine was about 1/2 pint low after the drive when idling in park within the temperature range).

Happy to answer any questions that you may have.

Note - this is not a complete fluid replacement. My ZF8 holds 9.5 QTs total and only 5.1QTs or so are dumped when removing the pan and replacing the filter. I did 3 dump and fills over the course of about 10K miles leaving about 10% old fluid in the system.

Here is a link to the ZF Document. The process starts on page 5:

https://aftermarket.zf.com/app/controller/ti/download/Binary/22f16dae-c571-11ec-a2e7-00505690da53.pdf
 

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Frznrth

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Thanks. That does answer a lot of my questions. I wonder a bit about the temp range. One video gives 40-45c or 104-113F as the optimal fill level. I know 86-122 is from ZF but does it sound a bit wide?
 
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Thanks. That does answer a lot of my questions. I wonder a bit about the temp range. One video gives 40-45c or 104-113F as the optimal fill level. I know 86-122 is from ZF but does it sound a bit wide?
No; 86°F is the minimum temperature for all of the solenoids and valves to open and allow the fluid to flow through all passages. 122°F is the highest temperature that does not have a large effect on fluid expansion such that you do not have a false reading.

I would take ZF's recommendation over internet information any day of the week.
 

Frznrth

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ZF’s advice sounds good to me.

Do they also recommend “spill and fill” to get the oil as pure as new?
 
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ZF’s advice sounds good to me.

Do they also recommend “spill and fill” to get the oil as pure as new?
Yes, I have not found any information on ZF recommending a flush using a pump system and of the 3 dealers I checked only 1 could do a flush, but they could not explain how they would maintain temperature AND not overpressure the system. At that point it was a hard pass and I opted to do it myself. Note that ZF recommends 60K fluid changes whereas FCA states lifetime fill.

I did 3 dump and fills to get to 10%; any more than that has a diminishing return from my point of view.

Here is the fluid at 50K and new:

20220521_175322.jpg
 
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ZF’s advice sounds good to me.

Do they also recommend “spill and fill” to get the oil as pure as new?
Pan drop only. You don't need to get it as pure as new. Even at 50k miles fluid analysis as shown that there's plenty of life in the fluid regardless of its color. My unit took 6 liters of fluid when I had it changed but I think it may have been a little low from the factory.

ZF stance on ATF life has been "lifetime" for normal driving or 8 yrs/50k-75k miles severe service (heavy towing, sporty or high speed driving). However, ZF revised their recommendation to 150k km (90k miles) or, if unknown vehicle history, high loads/temperatures a shorter interval may be better.

Personally I think because their previous recommendation had become so widely distributed for so many years and was counter to what the OE's had been saying for years ZF had been asked to make a revision.

 

Frznrth

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Thanks. The truck is far from “severe” for its use. A pan drop sounds good for now.
 
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Pan drop only. You don't need to get it as pure as new. Even at 50k miles fluid analysis as shown that there's plenty of life in the fluid regardless of its color. My unit took 6 liters of fluid when I had it changed but I think it may have been a little low from the factory.

ZF stance on ATF life has been "lifetime" for normal driving or 8 yrs/50k-75k miles severe service (heavy towing, sporty or high speed driving). However, ZF revised their recommendation to 150k km (90k miles) or, if unknown vehicle history, high loads/temperatures a shorter interval may be better.

Personally I think because their previous recommendation had become so widely distributed for so many years and was counter to what the OE's had been saying for years ZF had been asked to make a revision.

A fair amount of contradictions out there including some from ZF themselves.

I found 62K miles (100,000km) to be recommendation in more than 1 ZF document with no mention of severe vs. normal operation.

 
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A fair amount of contradictions out there including some from ZF themselves.

I found 62K miles (100,000km) to be recommendation in more than 1 ZF document with no mention of severe vs. normal operation.

There's a revision date for their recommendations so it's not so much contradiction. I gave the link to the most recent revision (1/2022) Your link trends with their previous recommendations.
 
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There's a revision date for their recommendations so it's not so much contradiction. I gave the link to the most recent revision (1/2022) Your link trends with their previous recommendations.
Yep; the one I posted only states 2022 with no revision date. With that said, I prefer to err on the side of earlier changes versus later if for nothing else but to remove the wear metals. The fluid at 50K was very dirty as shown in my other post versus new fluid. I have not seen that much of a transition with other transmissions (TH400, 4L80E, 6R80, 6R140) in only 50K miles.
 
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If I owned a car with an automatic, I'd change the fluid and filter every 50k miles. At 100k miles intervals I'd do a fluid exchange.
 
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