r/subaru • u/Character_Lab_8817 • 1h ago
r/subaru • u/Chippy569 • Jun 04 '24
Mechanical Help CVT Fluids: A Consolidated Thread
Hello r/subaru,
We've been seeing a big influx of questions about CVT fluids lately, with an average of 1-2 threads per day for about the past month. So, I've decided to make one consolidated thread about it. Future question posts about CVT fluid will be deferred to this thread. In response, I want to get as much information as possible into a single place, so users like yourself can make as informed of a choice as possible.
What is a CVT?
Let's start with the basics here. The Continuously-Variable Transmission, or CVT, does not work the same way as a "conventional" automatic transmission which you may have been used to previously. So let's start our journey with a conventional auto trans.
In an automatic transmission, there are a series of planetary gearsets. These gearsets will be surrounded by a number of hydraulically-actuated clutches. The hydraulic fluid inside of the clutches are controlled by the transmission computer, through a mechanism of valves that are controlled by solenoids. The solenoids and valves all exist in a component known as a "valve body." As the TCM commands certain valves to open or close, different clutches will be engaged which subsequently will control elements of the planetary gearsets. This is how your conventional automatic transmission achieves changing gear ratios.
In a CVT, by contrast, the gear ratio mechanism is a set of cone-shaped sheaves or "variators" with a belt (or in Subaru's case, chain) run between them. Instead of the valve body controlling clutch packs, it instead varies the fluid pressure inside of both sheaves, such that the cone surfaces can get closer together or further apart. Because the thickness of the chain doesn't change, by opening the sheaves, the chain will ride down lower into the cone shapes, thus being on a smaller diameter. Because the chain doesn't change length either, there needs to be a corresponding change to the opposite change to get closer together to make the chain ride on a larger-diameter part of the sheave. Thus, the transmission computer achieves different gearing ratios by adjusting the gap of both sheaves in tandem. If you're having trouble visualizing this, here is a good animation explaining the motion.
Before someone interjects, yes there are clutch sets inside of a CVT as well. Specifically in a Subaru transmission, there are 3 relevant ones; there is a planetary set inside the powerflow for your Drive or Reverse functionality; there is a Lock-Up clutch inside the torque converter, and in most cases there is a Multi-Plate Transfer clutch for your all-wheel drive "center differential" function. These functions are more-or-less identical to their equivalent components in a conventional automatic transmission.
OK but what about the fluid?
There are quite a few differences between CVT fluid and conventional ATF. Part of these differences are how the fluid is used in the transmission, and part of the difference is because of what the transmission does to the fluid.
In a conventional transmission, you have many clutch packs actuating whenever the car is changing gear ratios. Just like in a manual transmission clutch, or like your brake pads, every time there is slip between the clutch material and the friction surface, a little bit of that clutch material will wear off. In a conventional transmission, this means that over time, that clutch material will begin to accumulate in the fluid, which gives it a burnt smell and a brown tinge. By contrast, a CVT does not use as many clutches inside of it, and as such, clutch material contamination is drastically reduced inside of the CVT fluid.
Another main difference has to do with the fluid pressure inside of the transmission. While a conventional auto only needs fluid pressures around 150-250 PSI to operate the clutch packs, a CVT requires much higher line pressures of 650-850 PSI in order to keep enough "squeeze" force on the sheaves to hold the chain. The CVT fluid also functions as a friction modifier between the chain and sheave, wherein it helps the chain "grip" on the otherwise-smooth pulley surface. Because of this, CVT fluid is very specific about its chemical properties and should not be substituted for any other fluids.
So... should I service the fluid?
Let's start this by looking back at what a conventional automatic transmission requirement would be. Here is the service manual schedule from a 2010 Forester. I've highlighted ATF for you, but basically it only says "Inspect [and replace as necessary] every 30k miles." Okay, but what does it mean by Inspect? The service manual has this inspection procedure for checking the level. It also has this condition table listed for what to do when you find a condition-based failure. I've highlighted the "thick and varnish" section because this would be the clutch wear condition I described above. Generally speaking, your average Subaru 4EAT or 5EAT will have noticeable signs of discoloration every ~60k miles.
So what does Subaru say about CVT fluid then? Well for comparison, let's look at a 2018 Forester service manual. Here is the service schedule, which you can see has an identical "Inspect [and replace as necessary]" every 30k miles. As for an inspection process, it only offers this inspection procedure and the same condition table as before.
Because the schedule and condition checks are basically the same for both service manuals, it would be very easy to assume the fluids needs the same replacement schedule -- and I strongly suspect this is the driving force behind so many CVT fluid recommendations. However, if we read this again, remember that we only need to address the fluid if if fails one of the condition checks, and that the most common failure condition in a conventional automatic transmission largely no longer happens in a CVT. It is because of this that your Owner's Manual probably describes the transmission fluid as a "lifetime fluid."
What about what other countries say?
A claim I very often see made in threads about CVT fluid is that "Country XYZ requires fluid changes every X miles!" I want to nip this in the bud now, because it's not true. Now because I work in the US, I cannot access foreign service manuals, but I can get ahold of owner's manuals, so here are a few examples:
here's a UK 2018 forester owner's manual (link)
Here's a n Australian 2020 forester/XV schedule. Subaru Australiia has .pdf copies here of warranty booklets..
here's a Japan 2018 forester's owner's manual (link) and it says in the bottom row there: 交換時期 | 無交換 which translates as Replacement time | No replacement
Here is a 2020 WRX owner's manual from Japan, straight off Subaru.jp: https://www.subaru.jp/afterservice/tnst/wrx/pdf/A1760JJ-A.pdf
pg. 465 is the service information for transmission/differential/etc gear oils. The 3rd section is for CVT fluid:
トランスミッション フルード
使用オイル スバルハイトルクCVTフルード リニアトロニック用
規定量 約12.4L
交換時期 無交換
Translated:
Transmission Fluid
Used oil Subaru high torque CVT fluid for Lineartronic
Prescribed amount about 12.4L
Additionally, let's take a look at a 2011 legacy/outback service manual for comparison. Here's the maintenance schedule. The numbers inside the braces (「 」) are the severe schedule (which, with a CVT, only applies with "regular towing"), numbers without braces are the normal schedule. As you can see, CVTF only lists a severe schedule interval with no non-severe schedule. Exactly like in the US. Here is the same picture ran through google translate.
The only subaru branch AFAIK that does list a required CVT fluid interval is Canada, (soruce) where if I'm being honest the way it's written in their maintenance guide makes it seem like they just never changed it from ATF-era cars, where Canada also listed replacement as necessary every 100k km. (It only refers to "transmission oil" and does not specifically mention CVT fluid, but everywhere else differentiates the two. It also does not differentiate manual vs. automatic transmission fluid, like everyone else does.) There, it's listed as a 100k km service item.
that didn't answer the question though.
You're right, I didn't. The long answer is that you should have your fluid inspected by a technician familiar with Subaru CVTs, and if deemed necessary, you should replace the fluid with genuine Subaru fluid as required by your particular model. If following the conventional wisdom from ATF-era cars also makes you feel more comfortable, then defer to Canada's schedule and plan to perform a fluid service at your 100k km (60k miles) service.
A quick note about "Severe Usage Schedule"
Another common discussion point I see brought up is the Severe Usage schedule. I largely blame the confusion for this on Subaru, who have written this in a hard-to-understand way in the owner's manuals. However, a 2010-2014 Legacy/Outback service manual has the best representation of the severe usage shceudle. As you can see, the only time Severe applies to your CVTF is if you "repeatedly tow" with the vehicle. This guidance has not changed with newer cars, however the new way it's written is confusing to read. (CVT fluid is maintenance item 12; see above where it shows this as Note 4.)
A last quick note on Differential Fluid
Just want to quickly touch on this one. Your Subaru has separate, distinct fluid for the front differential. While you can see from the above service schedule that the guidance for its fluid is functionally the same, differential oil gets contaminated in a completely different way. Because a differential is basically all metal-on-metal wear of gear teeth, especially after break-in your fluid will get dark and metallic very rapidly. This is normal. Here's my personal Crosstrek at 19k miles. In my own personal experience, I would recommend replacing your gear oils at 30k miles, but the fluid condition will stay good for longer after the initial change, such that it can go every 60k thereafter.
On fluid changes and failures.
I just want to quick touch on ways that we see CVT failures at the dealer and how it relates to fluid. By far the most common issue we'll run across, is from the "small" CVT, the TR580, which is paired with any of the 2.0L or 2.5L naturally-aspirated engines. Typically somewhere in the 100-150k mile range, a failure in the valve body, usually for the Torque Converter Lockup Duty solenoid, is relatively common. This is a failure in the electronics side of the solenoid, and thus has no relation to the CVT fluid; as such, changing or not changing the fluid has no real bearing on the likelihood of this failure occuring. The second issue we see, the most terminal one, is called Chain Slip. Here, at 0:23, is a fantastic example of severe chain slip. Chain Slip can develop from a variety of causes, but generally is the result of a lack of fluid pressure squeezing the sheaves against the chain; when this happens, the chain essentially does a burnout on the sheaves. This leaves a wear groove in the sheave face, and makes chain slip much more likely to occur whenever the same gear ratio is used. There are some conditions of fluid degradation that can increase the risk of slip; these largely result from fluid overheating, which degrades the additives that help provide friction between the sheaves and chain.
Hopefully there is enough info in here for you to decide for yourself if or when you would like to change your fluid. Feel free to post your questions or anecdotes below. Thanks! :)
r/subaru • u/Chippy569 • 7d ago
Announcement New radio update available for CP1.5 vehicles
https://www.reddit.com/r/subaru/wiki/radios/cp15
- 23-25MY Outback/Legacy Models (including Wilderness models)
- 23-25MY Ascent Models
- 24-25MY Impreza
- 24-25MYCrosstrek (including Wilderness models)
- 24MY WRX
- 25MY Forester
From TSB 15-305-22R, update #5 is now available at dealers. If you have a 2025 Outback/Legacy and already did recall WRC-24, it did not include the rest of the fixes in this update.
This will eventually be available as an OTA update, no idea when though.
Update 5:
Release date: 3/24/2025
Version: FM1W*M174-880
Category: Reset
- If SXM was playing at the time of ignition-off, CID screen reboot occurs approximately 3 minutes after the ignition is turned on the next time.
- The system cannot recover when an error occurs during the Wi-Fi function startup process causing CID screen to turn black and freeze.
- Processing slows down and CP1 resets and restarts when following steps are performed: while listening SXM, go to Categories >Talk tab > Entertainment > On Demand list, press “Back” and repeat the list quickly and repeatedly.
- After the "Loading" icon appears on the CID screen, the CCU restarts, and the "Loading" icon continues to appear repeatedly.
- The CID screen resets within three minutes after turning the ignition on.
- After turning the ignition on, switching to the navigation (MAP) screen causes the navigation app to restart. This issue occurs when the destination suggestion feature is enabled.3
Category: Android Auto and CarPlay
- Following the steps below results in all smartphone connectivity features, including Android Auto and CarPlay, becoming unavailable:
- While using Android Auto via USB, shut down Android Auto while keeping the USB connection intact.
- After step 1, launch Wireless Android Auto while still connected via USB.
Category: CarPlay
- CarPlay fails to reconnect automatically when turning the ignition off while CarPlay is active or turning the ignition on when "See You" is displayed on the CID screen.
- The screen does not return to the CarPlay display and instead shows the CCU main screen (HOME screen).
- CarPlay cannot be launched. (Other functions, such as Android Auto, are available)
- When the maximum of seven smartphones are already registered, an additional smartphone is registered. On the newly added smartphone, call operations for CarPlay, such as answering, holding, and ending calls using the steering wheel switch, cannot be performed.
Category: Wi-Fi
- After starting the CCU, functions that use Wi-Fi connection with a smartphone, such as CarPlay and AndroidAuto, are not activated.
Category: Bluetooth
- When the WALKMAN NW-A100 series is connected via Bluetooth, the message ""Use Connected device to control playback"" is displayed on the CID's Bluetooth audio screen and playback controls from the CID are disabled while the audio can be heard without problem. Modify the system to allow playback controls from the CID as well.
- When an Android smartphone is connected via USB and Android Auto is launched, all Bluetooth-related functions become unavailable. This includes connecting, disconnecting, and deleting pairings.
Category: Media USB
- The data on the USB drive fails to play, when a USB drive contains only video files (without any audio files).
- When USB drive Audio is selected, "Loading Device..." continues to be displayed, and the loading process does not complete.
Category: Audio Output
- No sound from the speakers, after turning the ignition off while the driver’s door is open then turning the ignition on again within approximately 5 seconds.
Category: SXM
- The SXM channels changes before and after turning the ignition off/on.
- The word “Loading” is not displayed during the loading of the SXM screen and the field remains blank. The selected stations are displayed as usual only after the loading is completed. It occurs when you turn the ignition off with SXM (IP channel) playing and then turn the ignition on again.
- While playing the SXM Radio OnDemand channel, switching to another audio source such as radio or telephone, then switching back to SXM would cause playback to start from the beginning of the next episode.
- When the language used is switched according to the driver profile, SXM's Setting information is not switched, and registration/deletion of Notification, Favorite, and History information is not possible.
- In the above situation, if “College Football” is selected from the add screen of the "Team Notification" screen, the SXM application restarts and playback of channel 1 will begin approximately 90 seconds later.
- The SXM function becomes unresponsive, and the SXM app restarts. This condition occurs, if quickly switching back and forth between an SXM SAT channel that is not registered in the preset and an IP channel.
- No audio output, when switch the driver profile and then immediately changing the audio source while playing SXM.
- While playing SXM, pressing and holding the channel logo to add the channel to Favorites. Immediately after, switching the audio source to FM would cause audio output interruption.
Category: Radio
- When bookmarking a song during HD Radio Replay playback, the song information registered is not from the Replay playback but from the current Live playback.
Cateory: Navigation
- When searching for a destination in the navigation system, the address in the list only displays up to the postal code, state, and city, but the town name is not shown.
- The popup for switching connection to DCM which should only appear when starting a Map OTA update is incorrectly displayed when transitioning to the navigation screen.
- When registering a home address using the address search function, the retrieved address is displayed on the screen. However, if the user presses "Set" on the home registration screen, the system recalculates the address based on the latitude and longitude of the displayed location.
- (Example) If the user searches for ""7130 Orchard Rd"" and registers it as their home address, it is recorded as ""7134 Orchard Rd"" instead. This results in a discrepancy between the searched address and the registered home address.
- When launching the MAP application, only the CID screen background is displayed, and the MAP application does not appear. The system then returns to the HOME screen.
Category: Car Info Display
- When transitioning to the maintenance screen, the following two issues occur depending on the previous startup's maintenance settings:
- When maintenance was set to Auto in the previous startup: A subscription prompt popup appears despite an active subscription, and the setting switches to Manual.
- When maintenance was set to Manual in the previous startup: Pressing the Auto button triggers a subscription prompt popup, preventing the switch to
Category: Clock
- The clock shows incorrect time shifting by the same offset as the UTC difference. For example, if set to UTC+3, the time advances by 3 hours. Linked to a DCM malfunction preventing time information to be supplied to CCU the clock setting is switched from AUTO to MANUAL and back to AUTO in a vehicle not equipped with NAVI option.
Category: Meter Display
- Upon recovery from the EyeSight HALT error, the lane blinking display on the meter display flickers (the lane guide lines appear momentarily and then disappear).
- Turn by Turn (TBT) isplay on the meter screen does not appear and remains blank. However, this issue only affects the always-on TBT display, while the interrupt TBT during navigation guidance is displayed correctly on the meter.
Category: Log
- When users wanted to delete data logs (CCU internal operation logs), it was not possible to remove them through user operations. Deletion required performing the operation in Dealership Mode. Modify the specifications to enable DLT logs to be deleted through the Factory Data Reset operation.
Category: Reprogramming
- SWID verification fails at the start of reprogramming with SSM5, preventing the reprogramming process from starting. Note:The following issue also occurs due to a poor connection, failure, or data corruption of the USB memory used for reprogramming. In such cases, reinserting, replacing the USB memory, or re-downloading the data may resolve the issue.
r/subaru • u/_TommySalami • 2h ago
Subaru Generic Subaru Sponsored the Philly Cherry Blossom Festival
If you showed your key fob you got a bunch of swag, like a branded paper sakura umbrella to hand fans and coozies and reusable utensils in a case to keep in the glovebox for when you need to eat nachos in the car. Saw the new Forester but I had nachos and a dragonfruit beer so no photo
r/subaru • u/WolbergGT • 15h ago
Look what I found today!
A hot wheels subaru forester sti in world rally blue!
r/subaru • u/Funny_Arm_3401 • 7h ago
Car Mods Put a splitter on it. What do you guys think?
r/subaru • u/Trippinbillies40 • 8h ago
Subies and Sunsets
I got the car cleaned up yesterday and went out to experiment with off camera flash. Fun times!
r/subaru • u/United-Economist-01 • 4h ago
My Sti 2010
What do you guys think? bought it 8 months ago, it‘s completely stock with about 87000 miles on it
r/subaru • u/HarmsWayChad • 10m ago
Picked up my Arbor Day tree today!
Decided to go with the red maple.
Front passenger window stops intermittently when rolling up
Enable HLS to view with audio, or disable this notification
2014 Forester. Front passenger window can only be rolled down using the passenger button. Then stops intermittently when rolling up. Any ideas?
Mechanical Help Need help with my volume. Can’t change music volume for Apple CarPlay or radio. Dead silent. Every time I change the volume there’s an envelope with a down arrow.
2025 Subaru outback touring XT
r/subaru • u/castorMD • 1d ago
Will you buy a Subaru that is 8k higher ?
Do you have an update on Trump tarrifs and Subaru pricing... I know that some Subaru dealers are members of this Reddit and might have some insights
r/subaru • u/UnluckyAd4580 • 20h ago
Buying Advice First “new” Subaru - Which accessories or upgrades are 100% worth it?
First new-ish Subaru, 2024 Forester Sport. I previously drove a ‘94 Outback with 300k miles so this is an upgrade. About us: We have a golden retriever, and do a bit of camping and hiking (not a lot of off-roading or anything crazy). We also live in the low north east, so we do get some snow but nothing more than a few times a year. I want to put a little money into the car to keep it nice and prevent any scuffs we can.
Currently needing to buy the rear seat back protectors- specifically to keep the dog’s hair off of it. What else do you recommend? What was worth it? Any advice on where to buy accessories? I’m not picky and don’t have to stay w the Subaru branded merch- just don’t want to buy and have to return poorly made stuff or something that doesn’t actually fit the model.
Thank you!
r/subaru • u/OfficeChair70 • 23h ago
How old are you and what Subaru do you drive?
Title . How many other Subarus have you owned? Stolen from the Acura sub. How many miles?
r/subaru • u/chills18 • 1h ago
Can anyone tell me if this looks like a good deal?
I’m inexperienced in buying used cars. I currently have an ‘18 crosstrek with 80k miles. Looking for a bigger sized vehicle without breaking the bank.
r/subaru • u/Repulsive_Cover2418 • 1h ago
my new outback!!!
2010 3.6r outback :))) last pic is my 2006 outback whose engine died :( i’m gonna miss her but im so excited about this one!!!! coming up with new names
r/subaru • u/Brea_beard • 2h ago
Eyesight question
How do I get to the eyesight settings? I want to turn off the beeps it makes whenever a car merges in front of me.
r/subaru • u/Happy-Egg-1575 • 15h ago
Need help deciding if I should buy this GC8!
Is it worth it? - Found this GC8 on Facebook marketplace for 5800. For context I live in Vancouver, Canada. I took it for an inspection today to a Subaru specialist who mention there was a valve gasket leak, heavily rusted rear sway bar, heavily rusted break rotors, and is a JDM which apparently makes sourcing parts nearly impossible for these things, and incredibly expensive. He didn't even charge me for the inspection, told me it was so bad and asked me to leave, haha.
From what I see online the issues he mentioned aren't anything crazy, I sense the biggest expense would be labour to fix up the engine but I'm really not sure.
I'm a college student looking for his first car but also want's to build something overtime and invest in a build that I really like. Should I get it?
r/subaru • u/Austin_hskl • 3h ago
Mechanical Help Boxer engine problems
This is more of a generic quick head count for people with the subies with boxer 2.0 boxer engines and if they have had any problems with them.
I before buying my 2017 Impreza I looked around a lot for what to expect from them and the boxers seem to be a sorta polarizing topic. Some people think they are always gonna have problems and some never run into any issues. In my case, my car has pretty much always been maintained by the one person who owned it before me and I plan on carrying the torch.
I'm wondering if anyone has carried through with all the regular maintenance and still had head gasket or oil consumption problems with theirs? Feel free to leave your take too, I'm interested.
Thanks :)
Sedan Saturday Too late for FEF?
Last night at Larry Chen's Night Lights meet. Plenty of GR Supra, 86, and Corrolas.
r/subaru • u/Recent_Permit2653 • 8h ago
Subaru + wild weather = perfect
I’m sitting right underneath the temperature line, so we’ve had ternadie warnings (and some touching down within 45 min drive of here), rain for the last 24+ hours, and flood warnings.
My ole Legacy GT’s first wild and wooly weather event under my stewardship, and so far she’s a champ. It could not give less of a fluff about any of it.
Plus, it just looks like it belongs.
Stay safe out there. Don’t drive through water, and don’t waste time if a tornado’s warned. Stay in a low place, away from windows.
r/subaru • u/Robert_Mauro • 4h ago
No front skid plate, stock height, trying to tackle AOAA 4x4 Trails with my Ascent. Toughest downhill I've done that year.
Watch as Off Road Roos takes on the challenging trails of Anthracite Outdoor Adventure Area (AOAA) in Coal Township, PA, during our June 2024 summer adventure! Watch as a diverse group of Subarus navigate mud, rocks, and steep inclines.
This was especially tough for my Ascent, since I was at stock height without a front skid plate.
Featured Subarus:
- My 2019 Subaru Ascent (Stock height, no front skid plate!)
- Subaru Crosstrek Wilderness
- Subaru Outback Wilderness
- Classic 2004 Subaru Forester 2.5 XS
Experience the summer conditions at AOAA – see Puddle Road living up to its name (check our winter videos to see it frozen solid!). Witness the teamwork, careful spotting, and tactical driving required to conquer some of AOAA's most difficult Green trails, including steep climbs and descents like a challenging 25-degree incline.
First day trip ✅
Went to Joshua Tree and explored in my first new car, and first Subaru - a 2025 Outback Onyx XT. Absolutely loving it!
r/subaru • u/TurboWeldon • 4h ago
I need help finding a hose
I’m finally in the cusp of fixing my car to stop the misfires. But there is a tear in my vacuum hose which while small has caused some slight hesitance with my accelerating. But nothing terrible. I do also have a dip in idling if I’m driving a lot that day. I can’t find the hose anywhere online can anyone help me
r/subaru • u/DrRaptorYT • 5h ago
Chassis welded?
Hi guys. Is this line all around my suspension-chassis mount normal? The previous owner was a sketchy dude and I'm not sure if this is normal or not. I'm scared if the previous owner did any welding on the chassis. As you may notice I don't really know what a weld what would look like. Thanks in advance for any responses. Cheers🇹🇷
Buying Advice Looking for advice on 04 Outback h6
Planning on buying an 04 Outback H6, has 81k miles and needs a little work mainly ac and body work, no rust and located in north texas. wanting to know what would you price it at if it was mint?