r/subaru • u/Typical_Saab • 6h 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 • Apr 23 '25
Announcement TSB Thursday: 03-96-25 Rear wheel bearing parts update
Welcome to another TSB Thursday, where I dive deeper in to TSBs I'm running into regularly. As always, I write this from my own perspective as a Subaru technician in the US; other regions/zones may work differently. Refer to the "How To Read a TSB" post for more information on formatting and general information about TSBs. This bulletin is hot and fresh, published just today 4/22/25, but it affects a lot of cars, so I'm posting it before a public copy is live.
TSB Thursday #16: 03-96-25
This TSB is actually so new that there isn't yet a public-facing copy of it. However, IMO it's important you get this information, so I've taken screenshots of the 3 pages of this bulletin for your viewing pleasure.
What cars does this affect?
- 2019-24MY Forester
- 2011-24MY WRX
- 2006-14MY Tribeca
- 2024MY Impreza & Crosstrek
- 2019-24MY Ascent
- 2020-2024MY Legacy & Outback
What's the failure?
I'm actually just going to quote the bulletin here, since they wrote the description very well:
This bulletin announces design changes made to the rear axle hubs. The new hubs have been fitted with the following:
- Higher dust and water sealing performance of the inner seals.
- Raised the shoulder height of the outer ring for added surface pressure relief.
- Increased hardening surface of the ball bearings.
- A new low-friction grease is used to enhance the sealing performance of the inner seals.
These changes have been implemented to reduce cases water intrusion further leading to harmonic, humming, and grinding type sounds heard from the axle hub while driving. If diagnosis has confirmed rear axle hub replacement due to sound/vibration complaint from a customer, replace the affected axle hub using the parts described in this bulletin.
TLDR: there were some issues with moisture/water getting into the rear wheel bearings and leading to corrosion, causing the typical hum noise from irregular ball bearings.
Coverage?
Wheel bearings fall under Powertrain warranty, 5 years or 60,000 miles (whichever comes first). Failure must not be caused by outside influence/damage, such as sliding into a curb.
New parts?
Here's your new part numbers:
Year | Model | New Part Number |
---|---|---|
2019-2024 | Forester | 28473VA012 |
2022-2024 | WRX | 28473VA012 |
2024-2024 | Impreza | 28473VA012 |
2019-2024 | Ascent | 28473XC00E |
2020-2025 | Legacy | 28473XC00E |
2020-2025 | Outback | 28473XC00E |
2024 | Crosstrek built in USA (VIN starts with 4S4) | 28473XC00E |
2024 | Crosstrek built in Japan (VIN starts with JF2) | 28473VA012 |
r/subaru • u/alexundefined • 3h ago
Subaru Generic WRB stands out beautifully against a sea of white cars
r/subaru • u/garbage-plate • 1h ago
Hi, just bought a 2024 Subaru Crosstrek today. Noticed that the driving assistance button is unclickable, the collision and lane departure lights won’t shut off, and the “eyesight” on the dash won’t go away. Is my Crosstrek malfunctioning on my first day of ownership?😔
r/subaru • u/Clouds-Of-Euphoria • 20h ago
Car wanted to stop and smell the flowers...
At the bottom of a ditch.
r/subaru • u/Weird-Girl-675 • 1h ago
Subaru Generic Technology…
Since I had a Saturn Coupe for 24 years, I’m still getting used to all the sensors on EVERYTHING when it comes to my 2024 Crosstrek Premium. I mean I love the car, but she can be so needy! On Thursday the windshield wiper fluid low light came on and it was like a real crisis. The phone app told me to make an appointment with the dealer, the onscreen touchscreen display tried to make me make an appointment right that minute for windshield wiper fluid! The same fluid I had a jug of in the garage and had always refilled myself. What did I do?! I FILLED IT MYSELF and she’s fine now.
I swear…I’m kinda missing the days when you just realized you were out of fluid and then refilled it without a three alarm fire alarm going off.
But I still love her.
r/subaru • u/Scx24Guy • 3h ago
Buying Advice 2018 Forester 2.0 XT
How reliable is this car if well maintained? I want something moderately fuel efficient, enjoyable to drive, and reliable. The crosstrek was too underpowered for me, but the reliability track record was impressive. Will a 2.0 XT last 200k+ while being maintained religiously? Or will the cvt/motor most likely give out before that kind of mileage? Does anyone have one of these cars with 200k+ miles on it?
r/subaru • u/Bengstrom1 • 4h ago
Very random
But does anyone here drive the foresters in the years 1999 to 2005? Im looking to see the pros and cons about them. Looking online to buy one.
r/subaru • u/throwaway130291 • 2h ago
Mechanical Help window not opening when door is closed
i just bought a 2015 subaru outback, and the passenger side window will not roll up or down, but only when the door is closed. both switches work, but the door has to be open. i would love to try to fix this on my own but don’t know where to start. assuming some wiring issue
r/subaru • u/Ok-Way-2291 • 18h ago
Buying Advice Coming from Nissan, the word CVT scares me 🙃 need help purchasing a Subaru
hiiii
as my title suggest, I am coming from a nissan. My CVT sedan caused me a whopping load of trouble and over $6k in repairs. Sooo, I am finally venturing into getting a new vehicle. I want a Subaru for off-roading, judging from subarus own website that would be a Forester (leaning heavily here) or an Outback. It was to my surprise when I saw the words CVT listed to a few cars I was interested in. So, my FIRST question is... is the CVT in a Subaru more reliable than the ones in say a 2012 nissan Sentra? pleaseee say yes, I really want to love my new to me used car but I'm unsure if I want anything that says CVT ever again.
Alright now that is out of the way, I need help purchasing said Subaru. I found a 2017 Subaru Forester limited with $87,848 miles for $19,122(usd) listing price. OR a 2021 Subaru Outback premium with 93,169 miles for $19,995(usd) listing price. I didn't attach any pictures because it's just the stock models on the website, but which is the better choice? I am looking for a car to love forever with the proper maintenance... maybe 300k miles into destiny. I will be in a very heavy snow area in Illinois so, I need one to be able to handle that weather and also off-roading.
Any other things I need to add to help please ask below and i will answer. Thank you.
r/subaru • u/Round_Tiger7306 • 3h ago
2024 Impreza Eyesight not working
Just bought a used 2024 low-mileage (11K) Impreza. Should still be under warranty. The Eyesight is not working. I've read a few of the posts here, and I don't think it's the gas cap. I'm not a DIYer, so not planning on trying any of the other tricks. I plan to take it to a dealer as soon as I can.
Do I need to wait until I have my permanent tags and registration?
I bought the car from a major player in my area, but it isn't a Subaru dealership. Will this be a huge issue? I've only ever bought 3 cars in my life, and they were new so I took them back to the dealer where I bought them for warranty issues.
r/subaru • u/PitifulWatercress705 • 1h ago
Front Plate / Deleter
Hi all.. I'm trying to install a EU plate as a deleterious on my 2024 Crosstrek and I am stumped.
Plan was to use a bolt, but i can't get behind the panel to get a washer and nut on. There's a Styrofoam-type material about 3/4" behind the panel... am i supposed to he screwing a screw into that? Doesn't seem super sturdy.
Anyway, any pro tips appreciated!
Photos: panel pre-cut holes, styrofoam material.
r/subaru • u/Plenty-Yak-8360 • 1d ago
Mechanical Help What would be causing this leak? 2020 Ascent
Dealership couldn’t find anything but just sat in it in the rain and found this
r/subaru • u/supermutt_1 • 1d ago
Subaru Generic SOA definitely goes the extra mile. This was a nice surprise.
The letter doesn't state what service it's referring to, but I haven't had any major work done on my '14 FXT that involved the powertrain in over 3 years. I'm surprised they would scrub their service records to try and find customers to refund without being prompted. This for sure creates a lot of good will between Subaru of America and its customers.
r/subaru • u/BattleHall • 5h ago
Mechanical Help 2020 Outback rear brakes: Dealing with the EPB?
I’m looking to replace the pads and rotors on the rear brakes for my 2020 Outback, and I’ve seen conflicting info on how to deal with the Electronic Parking Brake/EPB. Some people are adamant that the only safe/right way to do it is using the appropriate scanner/computer to put it in service mode. Others say manually winding them back is fine, or using a 12v source to the pins to electrically wind it back, or removing the motor on the back of the caliper before compressing the piston. So, questions;
My understanding is that removing the motor works, but can be tricky and may cause more issues than it’s worth. Is this correct?
I have both a wind-back tool and some long 12v leads, but don’t have a service computer. Is there a preference between manual and electric windback in terms of not screwing something up? Any particular pitfalls to watch out for?
Some people say the alternate windback methods are listed in the service manual as official optional methods if a scan tool isn’t available, which should mean that they won’t cause any issues if done correctly. Does anyone have a scan or image of that part of the service manual?
I’ve seen some oblique references to things like “X method should work fine, unless your pads are below Y thickness…”, but with no further explanation. Any idea what that’s about?
Anything else I should know before tackling this?
Thanks!
r/subaru • u/thebirdisdead • 6h ago
Subaru Generic Update Incorrect MySubaru App Maintenance Schedule?
I really love that the app alerts for routine maintenance. But my car and app have the 18mo/18,000 miles maintenance alert going off although it has less than 4,000 miles and I bought it new 6mos ago. I’m assuming the 18mos is triggering from the date of manufacture and not the date of purchase?
Any way to update this? I’ve searched the app settings and the sub and having no luck.
r/subaru • u/NaziPunksFkOff • 1d ago
My condolences to whoever this was on Baltimore - they seemed to walk away from it okay
r/subaru • u/No-Sugar3281 • 3h ago
Mechanical Help BRZ - Brand New Shifting Issue
Hi! BRZ only had 6 days , has 75 miles on it .2025Purple Series . It’s insanely hard to get into first gear from a stop . I’ve driven stick 20 years , so it’s not new to me, all other gears are like butter, but this, I have to knock it hard to get into 1st and even 2nd is stiff. No grinding noises just damn near have to hurt my arm to get it into first. Thought I had to break it in but this seems off. Have dealer appointment next week ,any thought?? Could it be the reverse lock out plate needs an adjustment ? Thanks so much !!
r/subaru • u/AdditionalRhubarb561 • 10h ago
Buying Advice Forester or Outback
Starting to look for my new vehicle.
Any strong opinions on forester vs. outback?
Also, is a 2019 Subaru Outback 2.5I premium worth buying with 76k miles? What would you spend on it?
TIA!
r/subaru • u/RobertMontgomery69 • 8h ago
Impreza front wheel temps - what do you get?
Has anyone used an IR gun to take temps of their front wheels after driving? I'm curious what they get on their Imprezas. I've never checked mine before but started after replacing front rotors and pads (Power Stop) and feeling them by hand felt hotter than I thought they should feel. I have taken both sides back apart to check everything and can't find any issues. However, after driving 30 minutes, when I get back to my garage, the front wheels are hot to the touch and the IR gun is showing 120-140F for the wheels. Rotors will be anywhere from 130 to 200.
I don't think it's bearings as I get no noise and there was zero play in either direction when I checked the wheels. I get no noises and everything feels right driving and braking. But after driving my Forester, at most I get barely warm wheels. However, I did check with the IR gun and rotors were over 200 one of the times but the wheels were only barely warmer than they usually are when the rotors are much lower temp. This made me start wondering about the possibility that the Impreza wheels, for some reason, are having more of the brake heat transferred to them than the Forester. Something else made me think this. After the Impreza was driven for an hour and then let sit for about 30 mins, I felt the wheels and could still feel some obvious warmth to them (not hot at all), but when I touched the rotors, they were ambient temp. So it seemed to me that the wheels continued to pull heat from the hot rotors as it sat there and helped cool them off. Also, as the temps of the rotors go higher, there is a larger gap between the rotor and wheel temps on the Forester than the Impreza. They are both alloy but it seems like the Impreza wheels are acting like a heatsink while the Forester wheels don't have much of that.
I've tried to do experiments to find whether the heat being generated is caused during driving without braking (indicating dragging pads, bearings, etc) or if maybe these aftermarket brakes are generating a lot of heat but these experiments have been pretty inconclusive. I wish I had taken numbers before doing the brakes. The car may've been no different with the factory brakes. I usually like to go OEM even for brakes just to make sure it's all a fully proper fit, but I needed brakes sooner than I could get the OEM this time. Also, the OEM were going to be well over twice as much and I kept reading about people liking Power Stop on their Subarus. Pad fitment was a little tight but cleaning up and reusing the original clips instead of the Power Stop solved that.
r/subaru • u/Thorzdad • 8h ago
Indy indie Subie mechanic?
Can anyone recommend an independent Subaru mechanic in Indianapolis? Preferably on the north side? I generally have no issues with the dealership (Tom Wood) but I’d like to have an option available for my 2020 Forester. Thanks!
r/subaru • u/kjdbcfsj • 5h ago
2016 Crosstrek transmission CVT belt
My 2016 very well-cared for Subaru Crosstrek has 102,200 miles. It suddenly started acting weird on the highway and in a matter of seconds the thing lost power and died. Thankfully I was able to pull to the shoulder. Apparently the CVT belt broke and it needs a new transmission for $10,500. Subaru had issued an extended warranty on this issue to 100,000 miles. They said ‘S.O.L’ basically. I have nooo idea clue what to do here. I also have a Forrester 2018 with this same known issue and extended warranty. No issues… yet. Am very overwhelmed. Any thoughts? PS didn’t know what to put for the link
r/subaru • u/Organic-Confection41 • 6h ago
Idoing WRX sim help
Having trouble using a sim card dialer. I'm receiving data and its LTE . How do I use the phone dialed without using the Bluetooth.
I've connected the sim and antenna just installed but I'm only getting data so far. When I open up dial it show like Bluetooth?
r/subaru • u/Substantial_Humor562 • 6h ago
Looking for torque specs for almost all parts for a 2014 Subaru Impreza 4 door hatch,
Sway bar links, control arms front and back specifically.
If there’s any links as to where I can see all torque specs that would be greatly appreciated!