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2.0 D Oil Dilution

('14-'18) 
23K views 17 replies 6 participants last post by  kuato 
#1 ·
Hello, first post for me from Oz. I have a new forester which I find great to drive. Yesterday the DPF light came on flashing, no solid time. A few facts in point form

- just under 6k km on a new vehicle, had 1 month check np
- did a 300 km highway round trip the day before warning light started flashing
- extra urban driving mostly, average round trip 50km , recently started ( 2 weeks ago) driving it to work 50km round trip, half extra urban up to 80.
-no solid DPF light at any time - straight to flashing
- whilst driving it to the dealer , the flashing light went off and never came on again


I took the vehicle to the service centre and picked it up this afternoon. I was told the following;

- oil dilution caused the flashing DPF light. Oil change required.
- was told light went off after flashing over two different days because it was only teetering on the 10% threshold for the DPF light to flash
- that my driving habit was responsible for the quick march up of the oil dilution.
- that the revs up and down instead of steady revs and speed contributed to the early oil dilution.
- that driving the car in traffic or slow , even if I get to burn it off on a longer drive, is detrimental and caused the quick oil dilution rise. I asked if I can keep revs up (with the paddles) through traffic and was told the car would know Im not at speed regardless of revs(dont get this one)
-that the car will continue to be problematic for me and that it is not the right car for me and my driving habits.
- that a number of regens may have occurred on my longer 300km drive the day before which also ups oil dilution
- I asked for the DTC code but the service guy said they dont see those codes, just that the light was flashing and to bring it in any time it happens. Its under warranty.
- forgot to ask how many regens the car has done.



I have seen an old subaru bulletin related to euro 6 engines and ECU updating required related to oil dilution last year but my car was a september 16 build, should be up to date Id assume.

If anyone can explain to me how , with 6k of driving the oil dilution should be such an issue, even though roughly 3/4 of the ks the car has done have been extra urban I would be most grateful. Is it possible the engine is still loosening up? Perhaps the factory oil was not up to scratch or it was overfilled?

The service guy said that to solve the issue I need to drive at a steady highway speed not for the regens, but to avoid oil dilution too early as I understood it. Which means all the time.

I basically felt cornered that no matter what I do ,that the service guys are saying the car will not perform and im suspecting a broader issue related to the usability of the vehicle.

I understood buying a diesel I need to run it. But no one can run a car at one rev range, for one speed , all the time just to get to your next service without needing to change the oil half way along!

Regards and thanks for any answers , thoughts or experiences.
 
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#2 ·
Same thing happened to me mate, same kms too. Its just the thing you have to put up with and i have been trying to reduce excessive accelerating during the dpf regen as the injectors are injecting fuel at pre a post cylinder top dead centre as i have read in articles to increase dpf temp. So far so good. Basically the engine is running a lot richer during regen cycles so increasing revs suddenly can cause blowby which allows the diesel to pass through the cylinder and piston increasing oil dilution. Hope this helps.

Sent from my SM-G920I using Tapatalk
 
#4 ·
Hi kuato,

I have an older (2010) but hope I can help somewhat. You may wish to skim through my thread here. It should cover some of your issues: oil dilution, monitoring, regens, driving type.

Another great source of info is Subaru Diesel Crew

In the meantime here are a few points in answer to some of your queries. I'll start off with facts, and probably degenerate into one-eyed cynical opinions from there ;-)

  • Firstly, good luck with your new vehicle! There's been relatively few problems with the newer ones compared to mine, so I am hopeful you will be able to work through things to a successful conclusion (all right, started with an opinion :) ).
  • It is likely the service department is right about the oil dilution. I have had similar symptoms.
  • The flashing DPF light does not necessarily mean oil dilution (at least on my vehicle). You do need to have it investigated to determine the code.
  • You can read out the code. You can also read out the oil dilution and other parameters. However it may be the newer vehicles have stopped osme of the readouts, I am unsure.
  • The dealer will have been able to read out the oil dilution level and the code. Otherwise they wouldn't know and/or are rank incompetent and/or don't have the right equipment.
  • My dealer has reset the oil dilution and had us continue driving. However you need to be sure that's the right thing to do- diluted oil is never good and repeated episodes between oil changes are to be avoided.
  • Suburban driving on 60/80km/h roads should not be a problem. Stop-start driving is.
  • On our vehicle, urban and highway (like 110km/h freeway to sydney for 2.5hrs makes no difference.
  • On our vehicle, diesel quality makes a HUGE difference, in particular winterised (alpine) diesel available here in Canberra during winter.
  • However there have been many substantial changes between our vehicle and yours that should have addressed most, if not all, these issues.
  • It is typical, especially of dealers that do not know, to blame the driver. You could do 110km/h on the freeway all the time on cruise control and they'll still say its your fault. Or the earth's rotation changed, your compass is miscalibrated, the car doesn't like your choice of music/station. Anything but something wrong with the car.
  • Logging your data and presenting it to them makes them upset when they don't know what they're doing, but it may be your only defence. Except a good service manager, we've had one who considered our data and issues.
  • Subaru know about these issues. Our dealer even logged a drive (by me) using their software.
  • Revs up and down are not a major problem (at least on our older manual)
  • Urban and country driving is not a problem. The country driving allows a proper burn off, but it must be regular and often.
  • in general we get ~600km between regens when things are going properly, as low as 60km (on the freeway!) when not.
  • Other issues can cause excessive oil dilution, in our case a leaky intake elbow. You could do worse than to check for leaks e.g. a loose intake hose
  • The oil dilution is a calculated, not measured amount. Unlike petrol, diesel will not evaporate out of the oil...at least not until temps that will destroy the oil. Something like a leaky injector could actually make it worse that the reading.
  • If you've been sold the wrong vehicle for your driving you may actually have recourse under Australian Consumer Law.
  • The idea that you have to proceed at a particular revs and speed all the time (whilst sunnny, 22C and patting your hread nd rubbing your stomach (ie no hands on the wheel ;-) ) otherwise it's just not right for the vehicle and you're causing the oil dilution would qualify you for recourse under ACL as it's not fit for the purpose for which it was sold and does not meet reasonable consumer expectations!
  • The manual should tell you the conditions under which the DPF light will flash. This can include an overfull DPF (on ours)... so what they told you about just oil dilution is rubbish.
  • Your more modern model should report both regens completed and regens attempted (ours is completed only).
  • You may be able to reset the oil dilution yourself (or you couldn't change the oil yourself) BUT don't do anything whilst under warranty.
  • I think the dealers have been told to reset the oil dilution and "wag their finger at you" because of these issues.
  • Some others on here (see end of thread) are reporting petrol fuel economy figures that rival or better my diesel.

Hope this helps,
 
#6 ·
Thanks for the replies. Very informative. Im very interested in the process of active regen, namely what seems dodgy in my current opinion. My view reads as follows.

- active regen happens when the car is not being driven on long enough drives to cause passive regen. This means it is a function of the car, which means the car is meant to run at those speeds and loads. If the car was never meant to run for example below 80, then why have an active regen system which works at those speeds and loads?

- as I understand it active regens when unfinished at the time the car is turned off, are RESTARTED from scratch when the car is turned on and cool. The active regen is also then bumping up the oil dilution counter due to being recommenced. as I understand it.

- the car has a designated mode for slow speed offroading, XMode. This clarifies that the car is not only meant for driving under load over distance.

-There is no way for me to know my car is doing an active regen, therefore no way to manage it as a consumer.

I have contradicting views now as to how to drive my car.
-Initially I was told I should drive more than 20000 ks a year by two different salespeople at. No mention of the oil dilution issue at this point just soot clearing, which I felt confident I could manage, which I have in my opinion.
-The manual says nothing of ks, revs or slow driving, merely to take it out for a drive 80km/hr if the light goes solid which mine never has( I doubt it will as I suspect the active regen is overzealous in keeping soot under control at the expense of oil dilution)
- The service person said I need to drive it at steady revs and speed(perhaps he meant during active regens, which I cant know because there is no light to tell me same), and that holding the revs up at low speed will not cut it, and that my 50km round trip route to work(a dozen trips to date) is not appropriate for this.
- Then the Subaru website has this clause

'So again it is clear that a diesel engine vehicle requires a driving style and method of use that is only suitable for longer distances and higher loads!
This contradicts the car itself, which has a mode for slow speed driving called Xmode.

Im not trying to start a fight with subaru, but I am thoroughly confused as to how to care for or drive this vehicle now.
 
#7 ·
Id like to add a self quote and clarify something from my opening post;

'The service guy said that to solve the issue I need to drive at a steady highway speed not for the regens, but to avoid oil dilution too early as I understood it. Which means all the time.'

Id like to clarify that 'Which means all the time.' was my interpretation of how I was told the issue may be solved in relation to managing oil dilution and DPF in general. I got a science lesson at pickup which was most informative from the service guy, and his attempt to explain it to me was valiant, but its obviously complicated , confusing and beyond what a normal consumer normally understands of their inner workings of a vehicle, in my opinion.




.[/QUOTE]
 
#8 ·
Kuato,
...

...but its obviously complicated , confusing and beyond what a normal consumer normally understands of their inner workings of a vehicle, in my opinion.
I believe you are correct. Unfortunately it's getting beyond the (any) company's abilities to mange this issue with consumer expectations too- i.e., there are too many compromises not only for expectations, but for real world conditions.


Thanks for the replies. Very informative. Im very interested in the process of active regen, namely what seems dodgy in my current opinion. My view reads as follows.

- active regen happens when the car is not being driven on long enough drives to cause passive regen. This means it is a function of the car, which means the car is meant to run at those speeds and loads. If the car was never meant to run for example below 80, then why have an active regen system which works at those speeds and loads?

- as I understand it active regens when unfinished at the time the car is turned off, are RESTARTED from scratch when the car is turned on and cool. The active regen is also then bumping up the oil dilution counter due to being recommenced. as I understand it.
A couple of bits of information needed:
Firstly (simple) diesels generally have no throttle body but govern their output by the amount of fuel injected.
Secondly these more complex modern diesels don't just inject diesel. The can do so many times per cycle. For example there could be 5-7 or more injections of varying amounts at varying times during a single cycle, per cylinder. See here and scroll down to "Injections" for an example (and more info besides).

Three "types" of regen I know about are:
- Passive. Initiated when the exhaust temp gets high enough through normal driving. I can only initiate this through sustained hard driving uphill. The general EGT is arond 250-300C, it requires approx 425-450C and above to passively regen.
- Active. Initiated by the ECU under certain conditions. This involves 'post-injection', i.e. diesel is injected into the exhaust stroke. This is how it gets into the oil to dilute it. See here for a run down on Subaru diesels.
- Forced. Mechanic initiated, runs whilst parked by accelerating the engine whilst parked. Give the lie to "must drive above 80km/h to regen"

There are different ways of regenning. Note the regen is inexorably tied with the EURO4/5/6 emissions specs which also includes NOx emissions. Raising exhaust temp to burn soot results in increased NOx. This is alleviated by EGR to lower the O2 content in the exhaust. It also holds up the temp under coasting conditions. However diesels don't have a throttle body (simply/generally) as they regulate power by the amount of fuel injected....but you need a throttle to control air intake under regen conditions (not to mention whilst warming up when EGR helps too as does a restricted throttle) ...it goes on! Performance and fuel economy is restricted whilst all this is trying to be managed. You can perhaps now understand why the VW 'defeat' was perpetrated in order to maintain drivability and fuel economy.

In my case the regen initiated above "65%" soot at EGT>250C. The hysteresis is 10% so if you stop the engine and restart it then:
soot<55% the regen won't restart
soot >55% and EGT>250C it will restart/resume the regen.

Note there are also other regen conditions that can apply, notably the higher the soot level the lower the temp requirement.

Three methods I know of:
- post-injection. This is diesel injection into the exhaust stroke and is what takes place in the majority of consumer pax vehicles (I think). Cheapest as it simply requires reprogramming the engine with minimal extra equipment. This is what causes oil dilution.
- direct injection into the exhaust. Requires another injector, so extra $$$ which of course manufacturers avoid. Would mean no oil dilution too...
- Urea catalysis- selective catalytic reduction (SCR). Also known as "AdBlue" fluid (trade name). Some manufacturers have moved to this (M-B I believe is one) and commercial vehicles use it. Adds a small amount of urea to the exhaust system so that NOx are reduced and you can run an oversupply of O2 to burn soot. Requires (of course) a separate tank, monitoring, injection, all very $$$ for a manufacturer...

Note soot is a calculated amount. Basically they ECU measures the (inlet - outlet) pressure of the DPF, too big a differential and "it is determined" that a regen is necessary- the conditins vary, see here for a rundown of regen temp vs soot conditions and note the more serious "flashing DPF light"conditions that can occur. Soot level is temp dependent, i.e. needs calibration vs exhaust temp. If it's not calibrated properly it will vary simply with exhaust temp. Our car does this and I can watch the soot go above the trigger level coasting downhill with no injecting simply as the exhaust system cools under the full air flow; I have had temp decrease to ambient going down descending a mountain pass.

- the car has a designated mode for slow speed offroading, XMode. This clarifies that the car is not only meant for driving under load over distance.
Can't wait to hear the service dealer ask you to do 80km/h+ steady under X-Mode. And what happens when you ford a stream (that any 2WD car could) whilst the DPF is at 600+C (it shock cools and warps as one unfortunate driver reported once). Oh and my engine braking goes from minimal to practically non-existent under regen conditions. Isn't marketing wonderful?

-There is no way for me to know my car is doing an active regen, therefore no way to manage it as a consumer.
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Oh yes there could be, they just don't want you to know. They could easily install a light (or make the DPF glow e.g. green), just like cruise control, rear demister, park brake, etc. The only way to tell from any data available to you in the vehicle is likely to monitor the instantaneous fuel consumption. Get used to what it is reading, you will note a substantial increase during a regen. For example, if you do 6l/100km under steady running on a flat road, you may see an increase to e.g. 8 or 9l/100km. You can usually hear an engine note change plus response will be different (worse).


I have contradicting views now as to how to drive my car.
-Initially I was told I should drive more than 20000 ks a year by two different salespeople at. No mention of the oil dilution issue at this point just soot clearing, which I felt confident I could manage, which I have in my opinion.
It matters not one whit how many klms you drive. It only matters how you drive them. Park the car for 364 days/yr and it will not accumulate soot in the DPF except the day you drive it, do 500 country kms that day and you may get a regen (you may not). Do 20000km around the city in daily grind stop-start and you'll have a *lot* of problems.

-The manual says nothing of ks, revs or slow driving, merely to take it out for a drive 80km/hr if the light goes solid which mine never has( I doubt it will as I suspect the active regen is overzealous in keeping soot under control at the expense of oil dilution)
This is important. If you do what the manual says and it misbehaves it's the dealer/manufacturer's fault as you have met the required conditions and should have recourse to recompense/repair/refund. They will then say your fuel quality is to blame. If so ask them why they didn't raise it in the first place, prove it is so and also why they aren't selling cars able to deal with the local fuel, or perhaps more accurately, why there are selling cars that aren't able to deal with the local fuel.

- The service person said I need to drive it at steady revs and speed(perhaps he meant during active regens, which I cant know because there is no light to tell me same), and that holding the revs up at low speed will not cut it, and that my 50km round trip route to work(a dozen trips to date) is not appropriate for this.
Certainly running at a steady 100km/h is good for regenning. However we get acceptable results at a steady 60km/h in suburban traffic.

- Then the Subaru website has this clause

'So again it is clear that a diesel engine vehicle requires a driving style and method of use that is only suitable for longer distances and higher loads!
This contradicts the car itself, which has a mode for slow speed driving called Xmode.

Im not trying to start a fight with subaru, but I am thoroughly confused as to how to care for or drive this vehicle now.
I'm not surprised you are confused. The almost deliberate cross-purpose marketing leads persons (including me) to expectations different to actual vehicle performance under normal consumer usage.
 
#9 ·
So I have clarification from service that active regens are triggered only above 80, not 60, in this vehicle when the vehicle feels a regen is necessary given soot level , other operating conditions etc..I think there was a load requirement to stimulate the process also but could be wrong. Needless to say it sounds complicated. It therefore seems to differ to the active regens in the 2010 perhaps?Active and passive regens are not broken down from each other by the data readout, but incomplete and complete are. That hilly 80kmhr routes may affect the performance of a regen to render a hilly route with some long downhill unacceptable for this purpose(amazing) This is in line with pitracks measure of the temps on long downhills .

Active Regens as I see it wont occur until I kick on over 80, which is regularly, but I was told that perhaps up to three back to back burns would then possibly be initiated if I was on a long enough drive to deal with the soot from my slower driving. (Why then did my solid light never light up if I was such a soot hoarder?) Any indication as to how much soot gets cleared on a 12.5 min active regen percentage wise? As Ive read regens may add up to 1 % oil dilution or calculated oil dilution this means as low as ten 12.5 min burns might render my car as flashing lights and straight to dealer.

I am now informed use of x mode at slow speed requires offsetting other driving to facilitate the health of the system. As far as Im concerned the car has xmode it should be utilisable at any time. this to me means the petrol is a better offroad solution than the diesel.

I also received clarification that I would need OBD to read out data if I wanted to know whether an active regen is occurring. No way I as Subaru consumer can know this unless I provide additional equipment to the car it seems.


I wonder if an active burn shuts down if a passive burn can be initiated given favourable conditions? After all byways lead to highways . If it doesn't then that means an active burn may well kick off on the first leg of an otherwise appropriate passive burn route, upping oil dilution. Even if it shuts down in favour of passive burn conditions, could that active burn register as incomplete affecting the calculation for oil dilution? Any ideas more than welcome.
 
#10 ·
So I have clarification from service that active regens are triggered only above 80, not 60, in this vehicle when the vehicle feels a regen is necessary given soot level , other operating conditions etc..I think there was a load requirement to stimulate the process also but could be wrong. Needless to say it sounds complicated. It therefore seems to differ to the active regens in the 2010 perhaps?Active and passive regens are not broken down from each other by the data readout, but incomplete and complete are. That hilly 80kmhr routes may affect the performance of a regen to render a hilly route with some long downhill unacceptable for this purpose(amazing) This is in line with pitracks measure of the temps on long downhills .
Does sound different, yes. However the exhaust temp should be maintained downhill during a regen due to EGR and post-injection which takes place irrespective of accelerator position (at least in my vehicle), I can see this through the injected amount parameters.

Active Regens as I see it wont occur until I kick on over 80, which is regularly, but I was told that perhaps up to three back to back burns would then possibly be initiated if I was on a long enough drive to deal with the soot from my slower driving. (Why then did my solid light never light up if I was such a soot hoarder?) Any indication as to how much soot gets cleared on a 12.5 min active regen percentage wise? As Ive read regens may add up to 1 % oil dilution or calculated oil dilution this means as low as ten 12.5 min burns might render my car as flashing lights and straight to dealer.
I seem to have hit the 3 back-to-back burns too (see one of my posts here) but there was some time in between each.

The full soot load can be indicated to be cleaned. Whether it is or not I have my doubts given the seeming temp dependence (and perhaps other) of the soot load.


I am now informed use of x mode at slow speed requires offsetting other driving to facilitate the health of the system. As far as Im concerned the car has xmode it should be utilisable at any time. this to me means the petrol is a better offroad solution than the diesel.
Very likely.

I also received clarification that I would need OBD to read out data if I wanted to know whether an active regen is occurring. No way I as Subaru consumer can know this unless I provide additional equipment to the car it seems.
Cost is not high.

I wonder if an active burn shuts down if a passive burn can be initiated given favourable conditions? After all byways lead to highways . If it doesn't then that means an active burn may well kick off on the first leg of an otherwise appropriate passive burn route, upping oil dilution. Even if it shuts down in favour of passive burn conditions, could that active burn register as incomplete affecting the calculation for oil dilution? Any ideas more than welcome.
Passive burn simply means the soot burns off by itself under the current exhaust conditions, nothing extra needs to be done.

Active burn means the car changes something to start the soot burn.

Your car is more advanced than mine and may have various strategies mine doesn't esp. as EURO6 is more stringent than EURO5.

I can only offer what I know and have logged on mine (as well as my opinions of course which are worth the paper they're printed on... so $0.00! :biggrin: ).
 
#11 ·
Clarification of what I read in the manual after re reading.According to the manual it is preferred to drive at least 60km/hr for 15 mins or more with a warmed engine to run a regen if solid DPF light comes on , (noted if the solid DPF light comes on.) , Ive confused what the service gent has stated when a regen occurs being at 80. Apologies for confusion.

There is also some guidance in a different chapter for not driving at 15km/hr or less continuously as this will accumulate soot. Not that driving at 15 ks/hr continuously would be easy!

ta


Having thought long and hard Im getting the idea that the active regen system is not to be relied upon for repeated burns due to its tendency to oil dilution and the whole push to steady revs and higher speeds is to ensure drivers are using passive regens to keep the actives to a minimum.

Another interesting point , the manual does give guidance to not accelerate rapidly when regening with the solid light on. Its easy enough to manage this when the light has come on and you are trying to meet the conditions of a burn , you can adjust your acceleration exuberance.I find it interesting that the manual gives this guidance. Unless im mistaken, as an active burn may occur when the DPF solid light is off, the motorist may be accelerating to their hearts content unknowingly doing something the manual states not to do if the DPF light is on, unless of course there is some sort of difference between an active burn off of a nearer full DPF and one which is less full(no light on) which does not warrant acceleration management from the motorist. If not, then is it possible that oil dilution could be more of an issue with burn offs done under 'no solid light conditions'. Might explain how some people putt around at low speeds all month and then go for a burn when the dpf light is on and manage ok, whereas people who are driving generally faster longer more often may be unwittingly pumping the gas whilst doing burns as no light ever comes on, ending up with an oil dilution problem with no solid light precursor.

So whats missing? An 'oil dilution meter' or separate light for 'oil dilution warning' from the 'dpf warning light' , an 'active regen underway' light, or a 'control acceleration' dashlight.............. or all 3.
 
#13 · (Edited)
Yes, all I can say is that this all DPF thing regen sucks from consumer point of view.
Here is what I've done... I bought OBDLink Bluetooth adapter, got Torque Pro, install the PIDs pitrack_1 has posted in this thread and now I am able to see when the car has some business to do with the DPF (active regen). Do not get me wrong, I do not stare at this all the time while I am driving, I do check what is going on only from time to time...
But for me, the cure is to push the engine hard on the highway when you have the chance to do it. (Passive regen for our vehicles is hard to achieve, because "normal" DPF temperature is around 300C, but as pitrack_1 mentioned already you need it to be above 425C to start burning soot on its own). I manage to get it doing so, on a long ascent pushing the engine hard (the engine is really under load).

So the bottom line is: drive it, as you stole it on the highway :D
 
#14 · (Edited)
My mechanics told me last week (as i do lots of cold short distance driving during the week) to, once a week or every 2 weeks, take it on motorway and once the engine is hot pass on manual (cvt) in 4th or 5th and stay 15mn above 3000rpm to be 100% sure that the regen is done. According to him at this revs it creates a passive regen that avoid oil dilution increase...
Edit: this advice is given for plenty other brands of diesels euro6 engine apparently

I follow that instruction & i'll let you know if one day the dpf light comes on. (too early to say at the moment)

What is sure is that I believe this dpf thing is leading to the end of the diesel in europe (except for the ones that do a lot of highway driving)...previous dpf (euro 4 and euro5 regulation) were not as problematics, but, with the Euro6 it is a problem...it is becoming easier, without worries and finally cheaper, to run gasoline engine.
It is not a subaru specific...unfortunately, all brands have dpf issues with this new strictier norm.
 
#16 ·
Thanks for the experiences . It seems knowledge is power whether my car is running correctly or not. Personally I believe the manufacturer is underinforming the consumer on the dash, and in the manual. Im looking at the obd link lx adapter with torque pro. What are the values apart from instant consumption that this unit will/may give to me that will be of value in monitoring regens?

-Can I in any way monitor soot level ?
-dpf regens attempted and completed?
-If a regen is underway via a light?
-oil dilution calculation?

I did see pitracks sticky regarding active regen underway in the 2010 and getting a green light to come on? Anyone got a similar setup for a euro6?

Ive seen there is a 'km since dpf light flashing '- id assume that if this value blows out there are warranty issues. When if the consumer clears a code with obd/torque can their be warranty issues?
 
#17 ·
All you are asking is clearly visible on EURO6 diesel with pitracks PIDs for torque pro and obdlink lx adapter. I have it working on mine.

'km since dpf light flashing' - based on the manual you have to see the dealer ASAP, what is ASAP is not defined :)
Not to mention the fact that dealers are usually available next week...
 
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