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2017 Forester XT Touring CVT
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Discussion Starter · #1 ·
Proper procedure for CVT Fluid Change on FA20DIT equiped with CVT or 15+ WRX with automatic transmission (CVT) and 14-18 Forester xt (CVT).

14-18 Forester XT CVT Automatic Transmission, Fluid Change Procedure

Advice for all reading this, do this at a licensed mechanic shop, it does not have to be done by the Subaru dealer, no matter what any body on this forum says or what the dealer says. Everyone should read their warranty. Even though Subaru service and sales departments are saying that the fluid is good for the life of the transmission they are doing nothing but blowing smoke up everyones butt. Please read your owners manuals (Warranty and Maintenance Booklet page 31 Note "#4 under severe driving replace the CVT oil should be replaced under severe driving at 24,855 miles") it says transmission fluid service should be done at roughly 25k (24,855 miles after severe service) if vehicle is towing or has severe service. Rather vague on severe service.

Here is Subaru's definition of severe driving: Quoted from https://www.worldsubaru.com/subaru-maintenance-schedule.htm
"*Examples of Severe Driving Conditions:
•Repeated short distance driving.
•Driving on rough and/or muddy roads.
•Driving in dusty conditions.
•Driving in extremely cold weather.
•Driving in areas where road salts or other corrosive materials are used.
•Living in coastal areas.
•Repeated trailer towing."


To the point, fluid service is mentioned in the owners manual and the factory designed into the transmission a drain plug, a fill plug and created a fill and fluid level adjustment procedure. All that for something that was never to be serviced sound unbelievable.

So back on topic.

Do this with or at a licensed mechanic shop and get a receipt, this will CYA. Subaru extended warranty will accept work done by licensed mechanics, yes I know we can change our own oil and our warranty is not voided as long as we have receipts. This job is a little more complicated and I think the extra cost is worth not have the debate with Subaru of America if the transmission fails down the road. That could happen if you do or don’t touch the tranny.

To satisfy all the fear mongers about taking it to the dealer, I will say this YOUR ABSOLUTLY CORRECT. If anyone can afford and they trust their particular dealer then preferably do this at the dealer. Tell them you want a cvt fluid drain and fill. Mention all the argument up top and don't let them talk you out of it. Most dealers will try very hard to talk you out of it. It occured to me. I changed my mind after reading the maintenance book and also talking in back allys with subaru mechanics and studying and coming to understand how a cvt operates.

Parts list:
31728AA121 (transmission pan filter)
SOA748V0200 (5gal bucket of Subaru High Torque CVT Fluid)
803916010 (transmission drain plug crush washer)
803918060 (transmission fill plug gasket)
Permatex The Right Stuff

Labor Time for Professional 2HR

Must be done with the vehicle completly level!



1) Drain fluid, inspect for color and oder.

2) Remove fill plug at rear end of transmission case (allen plug)

3) Drop pan replace pan screen, clean magnet, clean pan well, remove all original subaru orange Gasket Maker (rtv). Clean pan with brake cleaner remove all metal particles and rtv debris. You should be able to eat on that pan. Use rags that won’t leave many fibers behind. That pan should have nothing not even dust in it when done. Just the nice clean magnet.

4) Clean off all original subaru orange gasket maker (rtv) material from mating surface on CVT. Wipe clean with brake cleaner. No brake cleaner in valve body or CVT. Just use it on a rag to remove oil and depris from mating surface.

5) Clean mating surface of transmission pan with rotary cleaning wheel, when done it should be clean shiny metal for the mating surface of the pan. Wipe clean with brake cleaner.

6) Apply Permatex " the right stuff " to the transmission pan, use this and read directions. Simply put it cures fast and the equipment can be returned to service immediately.

7) With a friend holding the pan up mate it to the bottom of the transmission. Before mating wipe clean any oil drips from mating surface of transmission case. Finger tighten screws, first do the corners.

8) Install remaining screws hand tight. Then lightly torque in cris cross pattern.

9) Lightly torque is super important. This is a steel screw going into aluminum. If you don’t understand lightly tight don’t do this. Sorry I don’t have torque specs for you.

10) Replace transmission pan drain plug, use new crush washer. This is the same crush washer used when changing the motor oil (same part #803916010). Torque to lightly tight.

11) Fill transmission through fill plug in rear of transmission. Fill with High Torque cvt fluid using a new pump. Do not contaminate cvt and cvt fluid with any foreign material or fluid.

12) Fill till fluid drips out fill port. Reinstall drain plug with original gasket lightly tighten.

13) Start engine and idle till transmission fluid temp comes to between 95f-113f. I found many service managers recommending 105f. Don’t use a thermometer or thermal gun. Use a vehicle diagnostic computer that can access transmission temp out of the TCU.

14) Run gear selector through the gears. R N D then D N R P. This ensures fluid is well circulated.

15) With engine running and transmission in park remove fill plug. Add cvt fluid to transmission till is drips out the fill plug. When it’s at a slow drip to no drip reinstall fill plug. Remove old gasket and use new gasket (part #803918060). Torque to light tight, torque spec 35 ft/lbs.

16) Clean everything up, clean off any splashed cvt fluid on transmission and exhaust.

17) Check for leaks and weeps. Tighten transmission pan drain plug if its leaking or weeping till leak/weep stops.

18) Now your going to need an advanced diagnostic computer. Most of us will have to go to a professional shop that has access to putting the transmission TCU through a relearn procedure. I’m not going to post what it is because all of you need to go to a proper professional mechanic for this. The procedure does only take 20 mins though and will have to be done with the transmission fluid temp around that 105f point mentioned earlier. If you had followed my advice and done this with a professional mechanic who can access this in the TCU then you done.

19) Tip your mechanic and have a beer. Drive lightly no WOT or quick acceleration for 50 miles let the transmission figure its self out with the new fluid.

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2019 Crosstrek 2018 Forester XT
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it does not have to be done by the Subaru dealer, no matter what any body on this forum says ]
For me discression is the better part of valor. And yes it would be difficult for the dealer to deny warranty but for a few extra bucks going to the dealer makes more sense (to me).

The end result is in both cases you are taking it to somewhere to have it done. Why not take it to a dealer where for another hundred your biggest concern is where to go for a coffee while the work is being done.

And for me I have an 8 year 80K mile warranty where I have zero problems.

I will admit that I do my oil changes but I get used oil analysis done periodically. And in a lot of ways changing my oil makes little sense. I will do it for a couple years and see how the oil analysis look and then let the dealer do it from then on. I will be 75 at that time.
 

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Discussion Starter · #4 ·
For me discression is the better part of valor. And yes it would be difficult for the dealer to deny warranty but for a few extra bucks going to the dealer makes more sense (to me).

The end result is in both cases you are taking it to somewhere to have it done. Why not take it to a dealer where for another hundred your biggest concern is where to go for a coffee while the work is being done.

And for me I have an 8 year 80K mile warranty where I have zero problems.

I will admit that I do my oil changes but I get used oil analysis done periodically. And in a lot of ways changing my oil makes little sense. I will do it for a couple years and see how the oil analysis look and then let the dealer do it from then on. I will be 75 at that time.
the best savings I found was around 300$ vs dealer. FYI

I mentioned it in the post though the best solution to this would be doing it at the dealer. But not all dealers have great mechanics or mechanics that simply check TSBs. I put this out there for the sharing of knowledge, maybe it will be found useful to others. An educated consumer will do better for themselves, as long as they recognize their own hubris and behave accordingly.
 

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Great information. Where is the source of your info? From the online shop manual? Looks like towing is the big qualifier for the CVT severe condition.
 

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2018 Forester XT
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In Canada...for Mitsubishi Evo's ... the fluid change and filter is approximately $1,100 for the SST Tranny

...and the Kicker is some guys do it every 20-30,000 KM
 

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Discussion Starter · #8 ·
Great information. Where is the source of your info? From the online shop manual? Looks like towing is the big qualifier for the CVT severe condition.

Talking with Subaru Dealer mechanics and access to fluid level check procedure and TCM relearn procedure at the my favorite local mechanic. Combine that with researching this forum and going through the parts schematic at parts.subaru.com. The last thing is just practical knowledge and experience of traditional transmission drain and fills.
 

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Discussion Starter · #9 ·
In Canada...for Mitsubishi Evo's ... the fluid change and filter is approximately $1,100 for the SST Tranny

...and the Kicker is some guys do it every 20-30,000 KM


I'm assuming you are referencing a dealer price parts and labor. Not parts price. I'm sure parts are expensive though.
 

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Where?
I googled the part # and its only $69.28 -31728AA121 (31728AA120)
Jorge
The part is often non factory online. It’s a German filter and the dealerships in Canada charge 270-290.

I got my factory oil and filter online from the us for about $600 though.
 

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Discussion Starter · #15 ·
Hi,
That's really odd.
https://parts.subaruonlineparts.com/oem-parts/subaru-oil-strainer-transmission-31728aa121
this is a Subaru OEM parts dealer.
Maybe is the wrong part number?
Jorge
great find!!!

i have built a relation ship with my chosen subaru dealer. saving 20$ this time is not worth it, when i have saved much more other times. i guess im ok with spending more to maintain a good relationship when i go for service visits.

but ill keep that in my hat for next time. perhaps i would hop on that find, next fluid drain and fill.

thanks for finding that for everyone.
 

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Discussion Starter · #16 ·

The part is often non factory online. It’s a German filter and the dealerships in Canada charge 270-290.

I got my factory oil and filter online from the us for about $600 though.

pm us next time you need one shipped. i cant believe they charged that much.

well let us know how your experience goes. i hope this thread helped you.
 

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2019 Crosstrek 2018 Forester XT
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I am very pro maintenance. I think change oil in a safe less invasive manner by drain and fills is a good idea. The filter change (to me) is questionable. Its unlikely that the filter will deteriorate and/or limit filtering within 200K miles. In fact it may actually filter better than a new one. Fluid oxidizes over time and replacing fluids are great.

If I were to do anything (which I will at say 40K miles). I will do a couple drain and fills. Prior to that I will install an exterior magnet and remove it prior to the drain.
 

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Discussion Starter · #18 · (Edited)
I am very pro maintenance. I think change oil in a safe less invasive manner by drain and fills is a good idea. The filter change (to me) is questionable. Its unlikely that the filter will deteriorate and/or limit filtering within 200K miles. In fact it may actually filter better than a new one. Fluid oxidizes over time and replacing fluids are great.

If I were to do anything (which I will at say 40K miles). I will do a couple drain and fills. Prior to that I will install an exterior magnet and remove it prior to the drain.
Totally agree with you. the filter that sits in the transmission pan is really just a screen to catch large contaminants. i guess im just so used to doing it in the past.

their is an internal magnet that does catch alot of ferrous material. an extra magnet or two on the outside is a good idea as well. i think 30 - 40K is a good interval for the CVT fluid, its expensive. if anyone frequently tows or does alot of short trips change it closer to 30K or sooner. remember the factory recommends around 23K, per sever duty maintenance schedule.

there is no clarity on frequency of towing.

i think towing once for 100 miles is not severe duty. but towing 30miles multiple times over those 30K miles might.

there is definitely some progressive relation.

im sure if you towed 100% of those 24K miles then that would be beyond severe duty.

any opinion
 

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2019 Crosstrek 2018 Forester XT
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I don't think even 1000 miles in the first 30K miles would be severe. I do plan on taking a used oil sample soon as a baseline.
 

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there is no clarity on frequency of towing.

i think towing once for 100 miles is not severe duty. but towing 30miles multiple times over those 30K miles might.

there is definitely some progressive relation.

im sure if you towed 100% of those 24K miles then that would be beyond severe duty.

any opinion
I don't think even 1000 miles in the first 30K miles would be severe. I do plan on taking a used oil sample soon as a baseline.
Remember, what you consider normal driving might be considered "severe" By SoA.

The only thing that matters is Subaru of America's definition of "Severe Duty." Familiarize yourself with that and if your driving habits or environment meet just one of those "Severe Duty" requirements, you must follow that set of intervals.

It may be that a good number of people are running a "Severe" duty cycle and don't even know it.
 
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