CVT Maintenance and Service Intervals

[Daskuppler]

Hello Everyone,

 

I searched the forum for similar threads and didn't see much other than the usual valid complaints from General Disorder.  This is just to help compile information, I don't currently have a problem.

That being said, the older CVTs were listed as lifetime fluids (we all know that's BS), and the newer ones have service intervals depending on use.  Not everyone can afford to just replace the transmission, so how do we take care of these the best that we can?

Should a complete power flush be performed every 30k miles for severe use?  Is an annual drain and fill sufficient?  What about at 60k miles?  There are a lot of fluids on the market now, is anything an acceptable substitution for Subaru fluid?  I know GD uses Amsoil and I trust them pretty much without question for all fluids.  Castrol, Valvoline, Redline, Motul, and I'm sure others, offer supposedly compatible CVT formulations.

If operating under sever duty, are temperatures an issue with these transmissions?  Should a cooler be installed?  Are there certain metrics that can/should be monitored by 3rd party devices?

These are clearly not built for towing or hauling, but are there other driving conditions that can cause excessive wear?  Using the transmission to engine brake, slipping (on snow/ice, off-roading, etc)?

What are common issues and their symptoms?  Are they preventable, or is it just luck of the draw?

 

Cheers,

Andrew

[forester2002s]

And another question: How much replacement CVT fluid is needed after draining the old fluid?

Subaru FSMs give the total amount of fluid required for a dry fill. But I have read that much less fluid is required after a simple maintenance drain. So how much fluid should one have on hand for the refill?

[Daskuppler]

9 minutes ago, forester2002s said:

And another question: How much replacement CVT fluid is needed after draining the old fluid?

Subaru FSMs give the total amount of fluid required for a dry fill. But I have read that much less fluid is required after a simple maintenance drain. So how much fluid should one have on hand for the refill?

In the past I believe I've put in 4-4.5 quarts. I always buy 6 and return 1. That's easy when you bought the fluid locally, but if you ordered something not so much. Temperature has to be about 100 degrees when you do the change though, otherwise you could overfill or underfill.

Edited December 2, 2022 by Daskuppler

[idosubaru]

On 12/2/2022 at 12:48 PM, Daskuppler said:

In the past I believe I've put in 4-4.5 quarts. I always buy 6 and return 1. That's easy when you bought the fluid locally, but if you ordered something not so much. Temperature has to be about 100 degrees when you do the change though, otherwise you could overfill or underfill.

I got Amsoil for mine. What I’m unsure of is can the first Amsoil fill be a partial drain fill or does it need to be a full evacuation?

I want to know what happens if you  just drain and fill and drive without following those specific directions?  What symptoms result?  For all the specificity I’ve never heard one person say they had issues.

Anything that requires something slecofic like that always has people posting online or calling me when they do it mistakenly. But not this time.

After 10 years of silence on that this suggests it’s a nonissue or overkill for very rare conditions or CYA for not having a dipstick?

Edited December 4, 2022 by idosubaru

[GeneralDisorder]

It's usually about 4-5 quarts. Complete fill when replacing the torque converter is about 8. 

No issues we have encountered from mixing Amsoil with the factory stuff. I just did a TC on a 2011 last weekend (bad thrust washer delaying TCC release), and filled it with Amsoil and customer reports perfect operation. 

Fluid needs to be filled at 105 to 110 to ensure proper level. We fill, run through gears, fill again, run through gears, power-brake (lightly) till trans temp comes up within range and fill last time then test drive. 

GD

Edited December 5, 2022 by GeneralDisorder

[GeneralDisorder]

3 minutes ago, GeneralDisorder said:

Fail

 

Edited December 5, 2022 by GeneralDisorder

[Numbchux]

We aimed for a drain-and-fill every 60k miles or so on my Mom's 2012 Impreza, Subaru fluid. It lasted about 220k. I guess that's good for an early TR580

[forester2002s]

2 hours ago, Numbchux said:

We aimed for a drain-and-fill every 60k miles or so on my Mom's 2012 Impreza, Subaru fluid. It lasted about 220k. I guess that's good for an early TR580

My 2017 Forester has the TR580.  Do you recall how much replacement fluid you needed for the drain-and-fill?

[Numbchux]

2 hours ago, forester2002s said:

My 2017 Forester has the TR580.  Do you recall how much replacement fluid you needed for the drain-and-fill?

I always bought 6 qts, and saved the receipt. Seems to me I usually returned 1, but the last time I used them all.

[Daskuppler]

On 12/3/2022 at 9:34 PM, idosubaru said:

I got Amsoil for mine. What I’m unsure of is can the first Amsoil fill be a partial drain fill or does it need to be a full evacuation?

I want to know what happens if you  just drain and fill and drive without following those specific directions?  What symptoms result?  For all the specificity I’ve never heard one person say they had issues.

Anything that requires something slecofic like that always has people posting online or calling me when they do it mistakenly. But not this time.

After 10 years of silence on that this suggests it’s a nonissue or overkill for very rare conditions or CYA for not having a dipstick?

There does seem to be quite a lot of hype over it.  My OBDII scanner gives live transmission temp so I follow it, but I agree, if it were a big issues, there would be a lot of failed transmissions from people draining hot fluid, measuring, then adding the equivalent in cold fluid back in.

[idosubaru]

18 hours ago, Daskuppler said:

There does seem to be quite a lot of hype over it.  My OBDII scanner gives live transmission temp so I follow it, but I agree, if it were a big issues, there would be a lot of failed transmissions from people draining hot fluid, measuring, then adding the equivalent in cold fluid back in.

Not just failed transmissions but zero symptoms from not following those instructions. There would be noise, shifting, codes, or other symptoms…if it was an issue. 

But quite literally none - not one person in 10 years has done just a drain and fill and had issues. And I guarantee it’s been done tons of times. I mean look at how many CVTs fail. 

It’s not definitive but highly suspicious. In 10 more years we will probably find out it didn’t matter. 

[Daskuppler]

Is it worth having the CVTs flushed periodically? Or is an annual drain and fill enough? 120k on my car and I've done a drain and fill annually for the last 4 years. Is a flush every 4 years better?

[idosubaru]

11 hours ago, Daskuppler said:

Is it worth having the CVTs flushed periodically? Or is an annual drain and fill enough? 120k on my car and I've done a drain and fill annually for the last 4 years. Is a flush every 4 years better?

Be nice to know what actual CVT failures happen and what causes, or prevents, them. 

Granted this isn't the same, but I think it would take strong evidence to convince people that short duration 1 quarter engine oil changes are better than a traditional full change.  So I'd guess a full change is *better*, but whether it matters or is worth the time is another thing. I don't think anyone knows the causative mechanisms behind CVT failure and what role fluid, if any, plays in it.  Does CVT fluid degrade, get overheated, or get particulate matter in it?

[Daskuppler]

1 hour ago, idosubaru said:

Be nice to know what actual CVT failures happen and what causes, or prevents, them. 

Granted this isn't the same, but I think it would take strong evidence to convince people that short duration 1 quarter engine oil changes are better than a traditional full change.  So I'd guess a full change is *better*, but whether it matters or is worth the time is another thing. I don't think anyone knows the causative mechanisms behind CVT failure and what role fluid, if any, plays in it.  Does CVT fluid degrade, get overheated, or get particulate matter in it?

From my research, it seems.like a drain and fill is the recommended procedure and even what the dealership frequently does. It sounds like a special machine is required to flush the CVT and the wrong one will ruin it.  Most failures seem to be the valve body, but who knows if that's a design thing or fluid related. I doubt it's fluid related as failures are all over the board mileage wise and it doesn't seem to be tied to poor maintenance. But again, there's not much official documentation.

These things seem to run pretty clean since there's not many clutches, but they do still need a change and Subaru recommends every 30k for severe duty, which is pretty much daily driving if you live in a city. They don't specify if that's a drain and fill it flush though.

Logic would say that draining 4.5 qts out of 13 and putting 4.5qts of fresh fluid back in leaves you with 13 qts of slightly less dirty fluid, but still dirty. Seems like you would have to do 4 or 5 drain and fills to have decent fluid again, which is a waste of fluid and time if it could just be flushed.

I find these cars very frustrating with the lack of information. It seems like everything was just out together with the hopes that they were right, but the engineers don't really know how it works or why it fails...which is just ludicrous. Maybe this is all because they don't want people working in them at home...

[forester2002s]

On my 2017 Forester (TR580 CVT), the periodic drain-&-refill only changes about 1/2 of the total CVT fluid.  The drain-plug is at the very bottom of the trans. And there's no mention of a CVT filter-change.

I wonder if the periodic drain-&-refill is not about refreshing the fluid, but is really about flushing out any wear-debris from the bottom of the case?

[Daskuppler]

14 minutes ago, forester2002s said:

On my 2017 Forester (TR580 CVT), the periodic drain-&-refill only changes about 1/2 of the total CVT fluid.  The drain-plug is at the very bottom of the trans. And there's no mention of a CVT filter-change.

I wonder if the periodic drain-&-refill is not about refreshing the fluid, but is really about flushing out any wear-debris from the bottom of the case?

That's a valid point.