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#4675692 - 02/23/18 04:57 PM Can my CVTF be too cold?
pilot1226 Offline


Registered: 06/26/17
Posts: 23
Loc: NJ
Hi all,

I'm running a 2011 Subaru Outback, 2.5i with CVT. The car's great, and I've been running RomRaider to pull the ATF temperature for the last week or two.

That being said, I'm finding that in my commute, about 10 miles each way to/from work which is 5 highway (65 mph) and 5 city (stop and go, posted speed limit 35 mph) - my CVTF is heating up from whatever the ambient is to around 110-120 F by the time I get home. I work shift work, so I have the benefit of driving to work at 4:30-5:00 AM when nobody's on the road but me, but I also have the "drive home" portion with moderate traffic. It takes about 25-30 minutes to get home on that 10 mile trip.

I know that temperatures above 210-220 F will start to leave varnish and lead to failure when done regularly.

So, I was surprised that the fluid never reaches a normalized level where the cooling mechanisms find a symbiosis with the temperature.

Now, here's where I'm confused. Normally, I'd say, "That's great! Heat is the number one killer of transmission fluid." And now, the curveball.

Subaru advertises their CVTF as lifetime fluid, unless you're towing. Obviously, towing must put a tremendous amount of stress on the fluid's lubricating and cooling properties.

However, Subaru Canada says that the CVTF must be changed about every 100,000 kilometers - or just over 60,000 miles. That falls in line with the major maintenance including spark plugs and other things for the boxer engines in their fleet.

I reached out to Subaru Canada about the interval. They say that because of the cold, the CVTF falls into a severe change schedule therefore requires a drain and fill every 100,000 kilometers. However, my Subaru USA booklet says it's only "severe" if you're towing for the purposes of CVTF.

So, that's where I'm confused. I would think that me being in a slightly more southern climate (NJ) is warmer (temperatures can exceed 100 F in the summer, and most of the time are 90 F or higher for June-July-August), and also get pretty cold in the winter (below freezing is expected for January-February)...

I don't tow, so that's good, but it got me thinking about the cold thermal properties of the CVTF. I've never had any type of irregular functioning of my CVT, but I'm still curious nonetheless.

My 2011 uses a "C-30" CVT from the factory fill. It takes about 12 quarts of fluid, but much of it is kept in the valve body and torque converter; as a result, if you do a drain-and-fill you're looking at somewhere around 6-7 quarts actually replaced. So, if you did a D&F at 60k miles, you've really got 50% of the fluid with 0 miles and 50% of the fluid with 60k miles still. Likewise if you did it again at 120k: 33% with 0, 33% with 60k, and 33% with 120k miles.

Modern Subaru CVT's now use CVTF-II fluid, which is green in color. It is backwards-compatible with the C-30 (blue in color). They also use a High-Torque CVT Fluid variant for their 3.6R (6-cylinder Boxer engine) and their XT (4-cylinder Turbo coupled with the FA DIT series engines). The high torque fluid is not compatible with the C-30 nor CVTF-II. There are several instances of people on the Subaru forums citing transmission failure and problems when using blends of the fluid when having the D&F done at non-Subaru shops. Doh!

I suppose the additive packages included with the proprietary CVTF are replenished which is usually a good thing, but at some point, it becomes a bad thing to replace old fluid because the fresh fluid can act like a solvent and disrupt some of the gunk otherwise encapsulated in the CVT and lead to valve body or solenoid failures, right?

I'm in the stages of buying a Subaru 3.6R next winter/spring, so I wanted to have a plan in place going forward for maintenance. I want this next car to last me a very long time. To me, these things aren't as disposable as people make them out to be. It's more than just an appliance or a thing, it becomes an extension of my very being, which is why I take great pride in doing my own maintenance and doing it properly. Not to digress from the purpose of this thread, I plan on running an OEM Subaru oil filter with Pennzoil Ultra Platinum 5w30 in it exclusively from the start.

So, does my CVTF never getting nearly up to "ideal" or "symbiotic" temperature cause problems?

Thanks, all. I appreciate your feedback.


Edited by pilot1226 (02/23/18 04:59 PM)
_________________________
Pilot, Subaru Ambassador
http://subaruoutback.org Forums

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#4675695 - 02/23/18 05:01 PM Re: Can my CVTF be too cold? [Re: pilot1226]
slacktide_bitog Offline


Registered: 03/20/08
Posts: 6135
Loc: USA
Castrol makes a good CVT fluid at a great price on Amazon. Occasionally, Autozone and AAP will have it on sale for $5/qt (AAP's sale just ended yesterday, but they do it a few times a year)

Going 200k without changing the fluid is MUCH worse than any compatibility issues between different brands of fluid smile

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#4675731 - 02/23/18 05:49 PM Re: Can my CVTF be too cold? [Re: pilot1226]
SubieRubyRoo Offline


Registered: 05/14/12
Posts: 1125
Loc: Winchester, Indiana
I doubt it specifically, but there isnít an automatic transmission or CVT on the market that iíd Go more than 60k between fluid changes; after a Honda 5-speed auto and Ford 6F35, 30k changes even with synthetic are extremely cheap insurance if you do it yourself.

Even at $10/quart, which would you prefer? $120 trans service or $3k+ trans replacement out of warranty?

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#4675893 - 02/23/18 08:30 PM Re: Can my CVTF be too cold? [Re: pilot1226]
TTK Offline


Registered: 10/23/07
Posts: 565
Loc: TN
Alaska is part of the USA and as cold as most of Canada. Also, there are towns in the USA and Canada that are close to each other. While I think the 60K miles is reasonable, there should be no difference between Canada and USA recommendations. What about Subaru of Mexico?
As far as your ATF temp, what do you expect it to be? Your engine coolant is probably near 200F, but the Subaru has a separate trans cooler independent of the radiator. It is directly in front of the passenger area in the engine bay. Your temps seem fine to me especially if you are not driving in mountains.
_________________________
2010 Volvo V70-3.2
Current Fill:Castrol Magnatec 5w-30
2018 Subaru Forester, 0w-20 Subaru oil
2001 Chevrolet Prism:Castrol Magnatec 5w-30


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#4676152 - 02/24/18 07:17 AM Re: Can my CVTF be too cold? [Re: SubieRubyRoo]
pilot1226 Offline


Registered: 06/26/17
Posts: 23
Loc: NJ
Originally Posted By: SubieRubyRoo
I doubt it specifically, but there isnít an automatic transmission or CVT on the market that iíd Go more than 60k between fluid changes; after a Honda 5-speed auto and Ford 6F35, 30k changes even with synthetic are extremely cheap insurance if you do it yourself.

Even at $10/quart, which would you prefer? $120 trans service or $3k+ trans replacement out of warranty?


Well I think it is a fundamental difference in the transmissions. If this were a regular ATF I would say 30k is probably the smart interval. But, the CVT is a sealed unit. Apparently there have been a few bulletins released by Subaru (TechTips Bulletins) that caution against introducing things from the outside into the CVT during maintenance (not that any of us would do the work with pets or in the middle of a rainstorm...) but it is assembled in a clean room.

Even to check the fluid level is a big production. Have to get the temperature between a certain level that you can only ascertain from an OBD2 ELM VAGCOM tool or the proprietary SST, and pump in fluid while the car is running into the check/fill valve from the bottom of the car.

These transmissions have been around for almost 10 years. Part of me thinks that if the fluid was truly 60k change interval, we would have seen countless claims of failure related to fluids and any and all new maintenance schedules would require a drain and fill interval.

I reached out to Amsoil regarding their CVT product. I believe theirs is just over 11 per quart and youíd need at least 7 quarts per D&F since you only get half the volume out. Waiting to hear back to them because as I mentioned in the first post he general CVTF II that Subaru is using does not appear to be compatible with the high torque variety. You also canít get the high torque fluid anywhere except the dealer in a 10 gallon barrel.

I would have to go get a battery fluid pump. No way Iím hand pumping 7 quarts into the CVT fill or check hole. Iíd be there all day.

@TTK your post mentioned you had one of the new Foresters. Whatís your plan for the CVTF (assuming you didnít get the 6MT)
_________________________
Pilot, Subaru Ambassador
http://subaruoutback.org Forums

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#4676628 - 02/24/18 03:00 PM Re: Can my CVTF be too cold? [Re: pilot1226]
TTK Offline


Registered: 10/23/07
Posts: 565
Loc: TN
@pilot1226 , I do not have a firm plan, but on the Forester Forum several have said their fluid looked good even at 100K miles.
_________________________
2010 Volvo V70-3.2
Current Fill:Castrol Magnatec 5w-30
2018 Subaru Forester, 0w-20 Subaru oil
2001 Chevrolet Prism:Castrol Magnatec 5w-30


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#4676834 - 02/24/18 06:32 PM Re: Can my CVTF be too cold? [Re: TTK]
pilot1226 Offline


Registered: 06/26/17
Posts: 23
Loc: NJ
Originally Posted By: TTK
@pilot1226 , I do not have a firm plan, but on the Forester Forum several have said their fluid looked good even at 100K miles.


Hearing the same thing. I'm upgrading to either a Legacy or Outback 3.6 in the spring of 2019, so I wanted to have a plan going forward. Think I'll let it ride myself!
_________________________
Pilot, Subaru Ambassador
http://subaruoutback.org Forums

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#4676960 - 02/24/18 08:47 PM Re: Can my CVTF be too cold? [Re: pilot1226]
zeng Offline


Registered: 09/01/15
Posts: 2183
Loc: Malaysia
Here is my 0.02.

Originally Posted By: pilot1226
I know that temperatures above 210-220 F will start to leave varnish and lead to failure when done regularly.
Yes, that may be true in IC engine systems with H2O as a combustion byproducts coupling with cool/cold valve cover and cylinder head temperatures.
Not quite in a transmission IMHO.

Quote:
Now, here's where I'm confused. Normally, I'd say, "That's great! Heat is the number one killer of transmission fluid." And now, the curveball.

Yes, heat as generated by boundary lubrication frictions due to too low an MOFT/operating viscosity is the killer.
110-120F is not, instead it provides thicker MOFT mitigating boundary lubrication and oil oxidation phenomena and that's positive.

Quote:
I reached out to Subaru Canada about the interval. They say that because of the cold, the CVTF falls into a severe change schedule therefore requires a drain and fill every 100,000 kilometers. However, my Subaru USA booklet says it's only "severe" if you're towing for the purposes of CVTF.
So, that's where I'm confused.

Subaru Canada, with due respect, is dishing out rubbish ... in the context of transmission operation mechanisms and Subaru USA.

Quote:
So, does my CVTF never getting nearly up to "ideal" or "symbiotic" temperature cause problems?

Absolutely no, at 110-120F from the perspective of components longevity.

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