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ZF 9-Speed Transmission Fluid and Transfer Case Fluid Change

30K views 177 replies 60 participants last post by  Dhefty1219  
#1 ·
I wouldn't say that I tow regularly, but I do tow my boxy travel trailer periodically. At about 40,000 miles on the clock, I'm halfway to Honda's recommended transmission and transfer case fluid change and I figured that it's now or never, so I decided to just go ahead and pull the trigger.

To prepare, I bought:
4 quarts of Honda Type 3.1 ATF 08200-9017 for $123.50 ($30.88 each!):

1 quart of Honda HGO-1 Gl-5 75W-85 Hypoid Gear Oil 08200-9014 for $26.08:

This 500cc oil pump for $12:

This 1-gallon graduated measuring pitcher for $23:

I also picked up this long funnel from Walmart:
Image



I decided to take a 2-pronged approach and use both weight and volume to determine how much fluid to replace, just for a nice gut-check that I'm not messing something up too horribly wrong.

First, using the pair of central jack points and a floor jack, I lifted both ends of the Ridgeline up and supported them with 4 jack stands.

Next, get the kitchen scale and weigh the empty 1-gallon pitcher at 11.7oz:
Image


Using a couple long extensions, an 8mm socket, and a section of 8mm Allen wrench from another project, I cracked the fill port open from the top side. Then from below, I cracked the drain port loose. I was able to hold the empty 1-gallon pitcher up directly under the drain hole as I unthreaded the drain plug by hand. Once the fluid was flowing, I just set the pitcher on the floor and let it drain out for a while.
Image


According to the 1-gallon pitcher, I got juuuuust over 124 fluid ounces of volume of fluid out:
Image


According to the kitchen scale, I got 109.40 oz of fluid out by weight (121.10oz - 11.7oz empty pitcher weight):
Image


The ZF 9-Speed drain and fill plugs have integrated gaskets. I realize that you're supposed to replace them at each fluid change, but I didn't see that as necessary.
Image


Image


Interestingly, the sealing washer on the lip of the plugs has a DIN number:
Image


"DIN 3869-18-FKM-dt"
DIN 3869 is a standard D-shaped washer. FKM is the material (Viton). 18 may indicate a size 18 washer. I wish now that I'd have grabbed my dial calipers and measured the washer for confirmation but this may be the exact washer at $13 for a 10-pack:
Otherwise if it's a size not available on Amazon, there are lots of standard sizes of this washer available for about 45 cents each, plus about $7 shipping.

Anyway, considering they want like $30 for one drain plug, just replacing the rubber washer on an otherwise fine plug seems like a very economical solution.

I weighed each new bottle of transmission fluid and poured 3 of them in, shaking them well first. Nice and green:
Image


Each bottle weighed 30.35 ounces when full and varied very slightly when empty, meaning that 3 bottles added up to 84.45 ounces, meaning that I needed to add 24.95 ounces (109.4 - 84.45) from the last bottle. That bottle started at 30.35 ounces, so it needed to weigh 5.40 ounces when done.
Image


As a side note, if that last bottle weighs 2.2 ounces empty, then that should leave 3.2 ounces (5.4 - 2.2) in the bottle. I found that each bottle contained about 28.15 ounces of fluid by weight. So if 28.15 ounces = 946ml (as printed on each bottle), then 3.2 ounces = 107.5 ml remaining in that last bottle. Looking at the sight scale on the side of the bottle, I'd say this checks out very well! The fluid line is just above 100ml.

Also, as another gut check, 107.5 ml / 946 ml = 11.37% of that quart bottle remaining. So by volume, the first 3 bottles are 32 fluid ounces and the last bottle is 28.36 fluid ounces (0.8863 * 32). That's 3 * 32 + 28.36 = 124.36 fluid ounces. I'd say that's exactly what the 1-gallon pitcher showed on its scale. Ok, I'm confident that weighing the ATF using the kitchen scale produced accurate results!

Then I moved on to change the transfer case fluid, which was fairly straightforward. I had two issues...

Issue 1:
My brand new 10mm square drain plug tool is the wrong size. I bought this tool:
I had read that the fill and drain plugs are NOT 3/8" square, but actually 10mm square. People had posted that a 3/8 drive will fit into the plug but it'll be a little loose and could increase the risk of stripping out the plug. So I bought the 10mm adapter. Well, in my case the adapter doesn't fit at all and a 3/8 extension fits perfectly in the square drain plug hole. So I don't know if Honda changed plugs somewhere along the line or if the rear diff is 10mm or what. But anyhow, I ended up just using a short socket extension on the transfer case which worked great. The plugs were pretty tight, but I had a 3/8" to 1/2" adapter on a long 1/2" ratchet which broke them loose pretty easily. I did not bother to replace the crush washers and instead just cleaned them and put them back together again.

Issue 2:
Because I bought the Honda fluid, the bottle had a mouth that was WAY too big to fit into the fill hole. Fortunately I had the fluid transfer pump thing noted above. I was able to suck over half of the quart bottle up into the pump and push it straight into the transfer case very easily. Then I squirted the remainder back into the bottle for use next time. @zroger73 gave the great advice to use a small pump sprayer instead, which I think is also a great idea! Just cut the tip of the wand off and shoot the fluid right in the hole.

After I got everything buttoned back up again, I then took the Ridgeline down off the jack stands and took it for a spin and noticed no difference in performance. I call that a win. Hopefully this helps someone else looking to save some cash by changing their own transmission and transfer case fluid.
 
#2 ·
Wow - what a detailed presentation of how to perform the trans/transfer case fluid change along with all associated materials. I only have about 3.6K miles on my RL in a year so it will be some time before the trans fluid requires servicing. The transfer case on my 2023 will need changing in maybe 3 years and I will bookmark your posting for reference when that time comes.

Thanks again for all your efforts and posting for others to follow.
 
#7 ·
@zroger73 gave the great advice to use a small pump sprayer instead, which I think is also a great idea! Just cut the tip of the wand off and shoot the fluid right in the hole.

Wisconsin-Mike,
That pump sprayer tip from zroger73 was useful to me also. Didn't spill a drop refilling the diff.
Gonna miss his posts!
I also read on ROC that 10mm fit the rear differential plugs which is not the case.
Luckily I got this set instead of the one socket since we have four vehicles in the fleet.

Haven't rolled up enough miles to do the trans yet.But thank you for ALL the great posts on maintenance and mods.
 
#10 ·
Nope 10mm doesn't fit the rear differential plugs. I read that also but luckily I purchased a set since I have Subies and a Toyota in the family fleet.
The 3/8" square plug socket in this set I purchased fits tighter than a 3/8" extension. That will keep you from rounding the plug fitting. Which I had done to my 1st Gen using extensions. Also handy if you have other makes of vehicles as I.
Image
 
#11 ·
Nice write up and I like your approach of double checking weight and volume.

This is very tangential comment, but related to that "DIN 3869-18-FKM-dt" sealing washer being made from FKM. I was happy to see that, since discovering how well Fluoro rubber works as a watch band material. The FKM has a heft, piliability, durability that is well suited to a heavier watch when compared to a strap made from Silicone and comes without the smell of Itialian rubber. So I can imagine FKM would work well as a transmission plug washer.
 
#13 · (Edited)
Mike, Great write up. When I did a transmission fluid update at about 24k miles, I just drained the oil into a measured pitcher and waited until the trans fluid was at ambient temperature to measure the volume of oil that I had drained out. My thought was that at the time of manufacture, the fill procedure was also likely at some factory ambient temperature and so the volume issues related to thermal expansion would be pretty similar. Your method was certainly a bit more precise but I didn't think to buy a scale and be that precise. I went back to review my service notes and a hot drain of the trans fluid produced an ambient level of 3.7 quarts after returning to ambient temperature. Our different techniques resulted in me using .1 quarts less of trans fluid (about 3 ounces less) which I can't imagine is that critical? Like yourself, I followed the recommendation to shake the trans fluid bottles before use to get the emulsifiers all mixed together.

Out of an abundance of caution, I bought one of the expensive OEM drain plugs and used it on the lower drain plug so that I did not have worry about any potential leaks and torqued them down to the precise OEM specs. The upper fill plug did not seem as critical because the fluid level is not topped off, based on the factory fill. I too did not notice any difference in performance which as you so aptly pointed out is a WIN!
 
#24 ·
I went back to review my service notes and a hot drain of the trans fluid produced an ambient level of 3.7 quarts after returning to ambient temperature. Our different techniques resulted in me using .1 quarts less of trans fluid (about 3 ounces less) which I can't imagine is that critical?
It is my understanding that the amount of ATF that comes out of the drain plug is variable because the torque converter weep hole varies its location every time you shut the engine off. That's why nobody can say, "Just drain the transmission and refill it with X amount of ATF." The amount is variable every time, even on the same vehicle.

But interestingly, I did see in a video that Jeep (which has the same ZF 9-speed) fills their transmissions fuller than Honda. So when in doubt, it appears that there is no harm is slightly over-filling.
 
#15 ·
Great write up! I have serviced the transmission, transfer and diff cases of my two GenI's countless numbers of times. Using the end of a 3/8 extension (seated fully by a lightly tapping it in place) has never failed to get the plugs loose and has never damaged the plug in the process. I have little doubt that the GenII's socket on the plug is exactly then same as the GenI and the tools with the square 3/8 end will work just fine.
 
#16 ·
Dumb question here……..what do you do with the used fluid? When I have taken used oil to Autozone they always are adamant that it’s for motor oil only. So what do we do with used transmission and differential fluids?
 
#20 ·
Here, the transfer station accepts everything plus the oil filters. Coolant you just leave in a separate container. I always thought they use the fluid for their heaters but I've seen a service come and pump the fluid from the tank. It's very convenient. In the past, when I lived elsewhere, returning to a store rarely worked as they usually said their tanks were full. As per NY law, they don't have to accept it if their tanks are full, so the name of the game is to keep them that way. I even tried returning to those oil change places and it was like a walk of shame, not easy.

I remember 35 years ago, I ripped a section of roof from my brother in law's house before raising it and disposed of it at that same transfer station which was the dump at the time. Now that area where I dumped the waste is a mountain with a solar farm on top. Ironically I now reside about a mile away from this transfer station, very convenient and a good way to save money compared to the waste companies. Ridgeline cones in handy for this purpose too. When I had the chocolate lab, the attendants there loved him.
 
#22 ·
Here, the transfer station accepts everything plus the oil filters. Coolant you just leave in a separate container. I always thought they use the fluid for their heaters but I've seen a service come and pump the fluid from the tank. It's very convenient. In the past, when I lived elsewhere, returning to a store rarely worked as they usually said their tanks were full. As per NY law, they don't have to accept it if their tanks are full, so the name of the game is to keep them that way. I even tried returning to those oil change places and it was like a walk of shame, not easy.

I remember 35 years ago, I ripped a section of roof from my brother in law's house before raising it and disposed of it at that same transfer station which was the dump at the time. Now that area where I dumped the waste is a mountain with a solar farm on top. Ironically I now reside about a mile away from this transfer station, very convenient and a good way to save money compared to the waste companies. Ridgeline cones in handy for this purpose too. When I had the chocolate lab, the attendants there loved him.
I live in a small town that doesn't have a landfill, but maybe they can tell me where I can take it.
 
#21 ·
Interesting. The Autozone near me takes used oil, transmission fluid, and gear oil. Their tank has a sign on it stating this and I have dropped transmission and used oil there before. Our county also has a dropoff site where you can leave containers of petroleum products as well as coolant and other hazardous materials such as paint and waste solvents.
 
#23 ·
You are correct on the DIN spec for the transmission hydrolic seals. The 18 doesn't necessarily mean 18 mm diameter. That is the 15.7mm ID in viton as you had found on Amazon. I looked into this recently and debated putting a 40K mile washer kit together for fluids for my new Gen2. Unfortunately, to get a really good price you do need to buy in bulk. The best price I found was for a lot of 100 and the (pre-shipping) price was about 30 cents each.
Maybe if I got a group buy together, I could build many kits and share the cost savings with a group that is interested. Not sure I could find 50 people that do their own transmission work though (2 seals per change). Surely it could fly for oil and even diff seals. They are relatively cheap anyway, but by the percentages, they can get way cheaper.
 
#27 ·
I'm pretty sure it said it on the Passport on bottom IIRC. That was very educational about the washer, but somewhere it was posted that the Stellantis plug is like 8 bucks. I remember when the 9 speed came out, ATF for it was like $40 bucks a quart, so it's a relief to see prices come down and know that a spill and fill is acceptable. Even BC auto solutions, (a youtube channel with a Honda tech) does the spill and fill method at the dealership.
 
#31 ·
I wouldn't say that I tow regularly, but I do tow my boxy travel trailer periodically. At about 40,000 miles on the clock, I'm halfway to Honda's recommended transmission and transfer case fluid change and I figured that it's now or never, so I decided to just go ahead and pull the trigger.

To prepare, I bought:
4 quarts of Honda Type 3.1 ATF 08200-9017 for $123.50 ($30.88 each!):

1 quart of Honda HGO-1 Gl-5 75W-85 Hypoid Gear Oil 08200-9014 for $26.08:

This 500cc oil pump for $12:

This 1-gallon graduated measuring pitcher for $23:

I also picked up this long funnel from Walmart:
View attachment 461182


I decided to take a 2-pronged approach and use both weight and volume to determine how much fluid to replace, just for a nice gut-check that I'm not messing something up too horribly wrong.

First, using the pair of central jack points and a floor jack, I lifted both ends of the Ridgeline up and supported them with 4 jack stands.

Next, get the kitchen scale and weigh the empty 1-gallon pitcher at 11.7oz:
View attachment 461177

Using a couple long extensions, an 8mm socket, and a section of 8mm Allen wrench from another project, I cracked the fill port open from the top side. Then from below, I cracked the drain port loose. I was able to hold the empty 1-gallon pitcher up directly under the drain hole as I unthreaded the drain plug by hand. Once the fluid was flowing, I just set the pitcher on the floor and let it drain out for a while.
View attachment 461178

According to the 1-gallon pitcher, I got juuuuust over 124 fluid ounces of volume of fluid out:
View attachment 461179

According to the kitchen scale, I got 109.40 oz of fluid out by weight (121.10oz - 11.7oz empty pitcher weight):
View attachment 461180

The ZF 9-Speed drain and fill plugs have integrated gaskets. I realize that you're supposed to replace them at each fluid change, but I didn't see that as necessary.
View attachment 461187

View attachment 461189

Interestingly, the sealing washer on the lip of the plugs has a DIN number:
View attachment 461188

"DIN 3869-18-FKM-dt"
DIN 3869 is a standard D-shaped washer. FKM is the material (Viton). 18 may indicate a size 18 washer. I wish now that I'd have grabbed my dial calipers and measured the washer for confirmation but this may be the exact washer at $13 for a 10-pack:
Otherwise if it's a size not available on Amazon, there are lots of standard sizes of this washer available for about 45 cents each, plus about $7 shipping.

Anyway, considering they want like $30 for one drain plug, just replacing the rubber washer on an otherwise fine plug seems like a very economical solution.

I weighed each new bottle of transmission fluid and poured 3 of them in, shaking them well first. Nice and green:
View attachment 461181

Each bottle weighed 30.35 ounces when full and varied very slightly when empty, meaning that 3 bottles added up to 84.45 ounces, meaning that I needed to add 24.95 ounces (109.4 - 84.45) from the last bottle. That bottle started at 30.35 ounces, so it needed to weigh 5.40 ounces when done.
View attachment 461183

As a side note, if that last bottle weighs 2.2 ounces empty, then that should leave 3.2 ounces (5.4 - 2.2) in the bottle. I found that each bottle contained about 28.15 ounces of fluid by weight. So if 28.15 ounces = 946ml (as printed on each bottle), then 3.2 ounces = 107.5 ml remaining in that last bottle. Looking at the sight scale on the side of the bottle, I'd say this checks out very well! The fluid line is just above 100ml.

Also, as another gut check, 107.5 ml / 946 ml = 11.37% of that quart bottle remaining. So by volume, the first 3 bottles are 32 fluid ounces and the last bottle is 28.36 fluid ounces (0.8863 * 32). That's 3 * 32 + 28.36 = 124.36 fluid ounces. I'd say that's exactly what the 1-gallon pitcher showed on its scale. Ok, I'm confident that weighing the ATF using the kitchen scale produced accurate results!

Then I moved on to change the transfer case fluid, which was fairly straightforward. I had two issues...

Issue 1:
My brand new 10mm square drain plug tool is the wrong size. I bought this tool:
I had read that the fill and drain plugs are NOT 3/8" square, but actually 10mm square. People had posted that a 3/8 drive will fit into the plug but it'll be a little loose and could increase the risk of stripping out the plug. So I bought the 10mm adapter. Well, in my case the adapter doesn't fit at all and a 3/8 extension fits perfectly in the square drain plug hole. So I don't know if Honda changed plugs somewhere along the line or if the rear diff is 10mm or what. But anyhow, I ended up just using a short socket extension on the transfer case which worked great. The plugs were pretty tight, but I had a 3/8" to 1/2" adapter on a long 1/2" ratchet which broke them loose pretty easily. I did not bother to replace the crush washers and instead just cleaned them and put them back together again.

Issue 2:
Because I bought the Honda fluid, the bottle had a mouth that was WAY too big to fit into the fill hole. Fortunately I had the fluid transfer pump thing noted above. I was able to suck over half of the quart bottle up into the pump and push it straight into the transfer case very easily. Then I squirted the remainder back into the bottle for use next time. @zroger73 gave the great advice to use a small pump sprayer instead, which I think is also a great idea! Just cut the tip of the wand off and shoot the fluid right in the hole.

After I got everything buttoned back up again, I then took the Ridgeline down off the jack stands and took it for a spin and noticed no difference in performance. I call that a win. Hopefully this helps someone else looking to save some cash by changing their own transmission and transfer case fluid.
Thank you for posting this!!!
 
#35 ·
Mike, thanks so much for that detailed write-up, especially since my 2022 is close to needing it's first transmission fluid change. I've changed all the other fluids in the past, including tranny fluid in our 2019 Ridgeline, but I heard the 9-speed tranny change is more complicated, so your procedures are fantastically timed.

Concerning dumping used fluids, I heard from a recycling guy once that they don't like it when we dump tranny and differential fluid into the oil recycling tanks. I only heard from this one guy and don't really know if that's true or not, but just in case, I always keep my other fluids for our twice a year amnesty day at the dump where you can bring just about any fluid!
 
#40 · (Edited)
For reference, here's a handy table that I came up with describing Ridgeline maintenance intervals.

Image


Note that each of these codes will appear only when the next oil change is within 15% of being due. For this reason it is very important to NOT reset the Maintenance Minder early, even if you choose to change your oil early. If the Maintenance Minder is continually reset early, then pending codes will never be displayed.
 
#42 ·
Morning Mike, So what your saying is all maintenance actions reset when you reset your oil early? I have a 2017 CRV and do the oil changes at 60% life due to oil dilution process. I have not seen it effect the other service maintenance scheduled changes on the computer. I love you table and will be posting it in my shop for future use on the 23 Ridgeline. I wish they would put that table back in the owners manual. I never take my autos to the dealer as I don't trust people messing with my car and the cost is getting crazy.
 
#41 ·
As I tow a lot I have done my (2020) tranny 3X in 55k miles, always with the truck and oil at ambient/room temp ( basically both in the garage, first thing in the morning before the day's heat hits....) so the CTE is not a factor with like temperature fluids. This does 'assume' that the factory filled it correctly the first time, of course. I put in the same volume- not weight, that comes out each time. I have never replaced the drain plug nor washer, and its never leaked a drop. YMMV. I use ZF Lifeguard 9 each time, generally buy a 6 pack of it online about 140 bucks, which is 1.5 changes or so. 3/8" drive socket fits all the plugs.
 
#45 ·
Thumbs up OP for this thread. My 2022 has about 50k on it now so I will be doing this soon.

I may have missed it in this thread, but what is the actual, correct process for checking fluid level in the ZF9?

In my gen 2 Tacoma, the process started with getting a scan tool with a PID for transmission fluid temp. Then bring the atf to the correct temp, and then remove the level check bolt on the transmission. When The flow slowed to a trickle, that was at the correct level. Too high or too low of temp and the measurement would be wrong.

Something similar for the Honda?
 
#46 · (Edited)
@Wisconsin_Mike :
Thanks for the write-up
I was across the country towing a cargo trailer with my '18 gen2 RL when the (6spd) trans over heated warning light came on :oops:.
I pulled over and left it running until that warning went out.
I finished the trip babying it at or below the posted speed limits. :confused:
5x8 shallow V-nosed Cargo trailer:
Image

When I returned home, I had it scanned at the stealership, it showed no codes so had the trans drained and refilled.
Upon inspection back home, the drain plug had no indication of ever being removed so I can only assume the dealer sucked the fluid out from the dipstick hole or fill plug. :confused:
There was no mention of any fluid burnt smell.
I installed a scan gage to monitor the trans fluid temp.
I saw a temp of 350F while creeping around in the mountains of Idaho, and the warning light had not came on. :oops:
I have since installed a 2x trans cooler in series with the OEM cooler but have not towed with it yet.
Kenstone