Engine Oil Change (DPF models)

Owners want to be able to change oil by themselves obviously.
On closed-type DPF models (all except MY 2008/2009 Legacy/Outback which are mated with open-type DPF) you’ll need to reset oil dilution parameter as it is calculated (not measured!) by the ECU. Basically active DPF regenerations in particular cause diesel fuel bypass into engine oil. Piston rings cannot seal perfectly.

No auto-detection! Since Subaru diesels, unlike Mazda for example, are not equipped with an oil pressure sensor, its software cannot detect an oil change nor deteriorated engine oil. Subaru’s simple on/off oil pressure switch (near oil filter) is connected to the dashboard. There’s also a low/high oil level switch available on Euro 5/6 models which won’t help here, too, although this one is evaluated by complex ECU algorithm.

Following info as seen in all managed-DPF-ROMs so far.

DTC P1468 Oil dilution (MIL remains off) is being triggered when oil dilution ratio ≥ 10 %. Results in DPF light flashing , there is no warning in advance! If oil dilution gets below 10 % (estimated evaporation) the light will also turn off.

The engine management software assumes 6.13 kg oil mass and this maintenance operation resets RAM variable “Oil Dilution Amount [kg]” to zero.
The ROM’s internal calculation steps are:

  1. update OilDilutionAmount [kg] according to CoolantTemp, Injection Quantities etc.
  2. OilDilutionRatio [%] = 100 * OilDilutionAmount [kg] / 6.13 [kg]
  3. EstimatedDistanceToOilChange [km], via LUT

Also see posts Estimated Distance to Oil Change as well as Oil Dilution Graph.

Oil Dilution Reset

We’ve traced related Euro 4/5/6 ECU-ROM machine code. Here are all possible options:

Euro 4 (IV)

  1. Diagnostic protocol (SSM2 via Serial only). See post Oil Dilution Reset (K-Line, Euro4). There is no alternative method on Euro 4 models! (In theory, we could patch Euro 4 ROMs adding the same Euro 5/6 manual procedure as below. Not a trivial task, though, talk about hours of development and testing…)

Euro 5 (V), Euro 6 (VI)

  1. Diagnostic protocol (Extended OBD-II only since advanced stuff is not implemented in SSM2 anymore unlike Euro 4)
  2. Manual procedure, should be printed in the owner’s manual. The following table is derived from actual ECU software, confirmed in Euro 5 gen2/gen3 and Euro 6 ROMs:
    Step Description
    Prerequisites Brake Light
    • Whole procedure must be done while parking.
    • Engine must be running.
    • Parking brake recommended, vehicle speed must be zero all the time.
    1 Depress and keep holding brake pedal. (Slight pressure is sufficient).
    2 (Rear) defogger ON
    3 Lights ON (stage 1 = parking/clearance/DRL lights is sufficient)
    From here you only have 4 seconds to accomplish each of the following steps and roughly half a minute total countdown!
    4 Defogger OFF
    5 Lights OFF
    6 Defogger ON (again)
    7 Lights ON (again)
    8 Defogger OFF
    9 Lights OFF
    10 Release brake pedal.
    Now the glow light (depicting yellow coil) will flash for 5 seconds indicating full success.
    Otherwise wait for half a minute at least, then try again, repeating the whole procedure.

    Many users have confirmed this procedure, e.g. Subaru Forester Owners Forum – Oil change on Diesel engine and ECU service reset.

    Wanted – please contribute:

    • dashboard video to confirm glow light flashing modes
    • picture of car owner’s manual page describing reset procedure

Other Brands

Mazda SkyActiv-D 2.2 (CX-5)

“Engine Oil Data Reset”, either via OBD or manual procedure (test terminal & accelerator pedal).

ECU software contains algorithms that can detect deteriorated engine oil via oil pressure sensor, there are several DTCs.


31 responses to “Engine Oil Change (DPF models)

  1. Good work!

    I’ve been told that the *need* for oil resets is disabled on UK models for legal reasons. Certainly I have only had the dealer reset the counter twice in almost 60k miles, with 25k miles before the first reset. But oil was changed every 10k.
    I’m now monitoring soot/ash/dilution using FreeSSM and look forward to seeing what happens when distance-to-change turns minus.


    • Could be – there might be a switch byte. ECU code looks up/considers a huge amount of things…
      Can you tell your ROM version (ROMID at least, displayed by FreeSSM and RomRaider)?
      What oil dilution ratios do you get so far?
      Possibly, depending on driving conditions, it might never get very high.


  2. ROM ID is 61 44 D8 73 07

    At 8k miles on the oil, and about 3k since an oil counter reset, it’s showing the next oilchange as due in 11k km. Oil dilution is currently 3%, total ash 19%.
    278 regens are recorded.


    • Well done. Your ROM must be successor of CALID JP3F501A = ROMID 61 44 D8 72 07 then, Forester MY09/10 ? Don’t have this one yet.
      Your oil dilution is low, ash & regens probably are ok for such big mileage.
      Did you try RomRaider + diesel logger defs? If RAM variable addresses do still match, you’d get more detailed numbers if you like. If they don’t – no harm done – except seeing bad values.
      Update: You’ll have to change ROMID (ecuid) in the RR-XML to match yours, then RR should display “extended” parameters.


  3. Hi,
    I have one extra ECU for my Suby diesel. I will be fine to let somebody play with it as long as I take it back without the immo, dpf,egr removed 🙂 .



  4. Hey, I have a 2008 outback diesel. I just got the scanguage 2 tool. Is there any way to determine if My model requires oil dilution reset? And if so, can it be done with the scanguage ?


    • If it’s really model year 2008 you have, the solution is simple: nothing to do.
      AFAIK 2008 Legacy/Outback have closed-type DPF, meaning there’s no DPF pressure difference sensor, not even exhaust gas temperatures, no active DPF regenerations, no (increased) oil dilution, no DPF/oil related (electronic) maintenance at all…
      Plz send us pic of your engine, especially DPF. If DPF does not have cables and hoses attached, it’s closed-type and ECU does not know anything about it.


  5. It seems that Subaru has problems calculating Oil dilution ration. Mine Euro4 Forester reached 10% oil dilution ration in 3k km after oil change. At the service they have reprogram the car, so the counter should be reset.
    I have 10% oil dilution ratio, 4% DPF cumulative Ash ratio, 28% soot accumulation ratio and 284 regens at 44k kms total.
    I usually do 150km trips at 130km/h.
    Bug in algorithm? I just noticed that it has been trying to do injector calibration for the last 1400km-s (now it finally managed to do it).


  6. Is it possible to reset oil dilution parameter using freessm or RomRaider? If its possible please send me details. I already change engine oil but oil dilution is >10% and estimated km to engine oil is 0.


    • I have the same problem….any solutions found by now…?
      DPF light just star to flash and freeSSM showes “P1468 Oil dilution” error. I gues I have to reset the “oil dilution parameter”, but my car is forester MY08 (EURO4) and this manual reset don`t do the magic….??…..is there any other way to reset this parameter without going to subaru…??
      OR can I just ignore flashing DPF light….??


  7. “If there were enough interest & donations we could develop and release maintenance software.”

    where can I send a donation to have maintenance software to reset the oil dilution counter? I already have the VAG-COM cable and can read data from the ECU with the freeSSM software, implementing the SSM2 protocol. Mine is a 2010 EURO4 diesel Forester and can provide engine type, ROM-ID, registered VIN as read by freeSSM.
    Any help much much appreciated.


  8. Hi,a little confused here, I have a UK Forester diesel registered in Sept. 09 (59 plate) and I am due to change the oil and I,m not sure if I need to do a ecu reset.I have tried the manual reset with a sequence of switches but that doesn’t work.My question is do UK models need reset? How can I get it reset without going to Subaru.


  9. In my car (forester diesel EURO4) the DPF light started to flash (oil delution error)…..oil delution is 10%. Is there a way to reset this parameter without going to Subaru?
    How long till going in limp-home mode without reseting this….?



    • Last time when i changed oil I didnt reset ECU (i didn’t visit Subaru service) ….. DPF light was turn on for a period of couple of days (around 100 km) then its gone. Probably the latest ROM (ROM-ID 61 44 D8 76 07 ) has a learning mechanisms and recognise that oil is changed. It is interesting that last time i used high quality fully synthetic oil (Mobil 1 ESP Formula 5w-30) and mann hummel oil filter so till now i have around 13 000 km and status on freessm “Estimated Distance to oil change ” is 6100 :-). With this combination of Oil and oil filter i can confirm that i have no issues with DPF. Next time i will do the same procedure hopefully will be successful.


  10. Since my last comment I solved my problem by buying a Select Monitor III, it works, it’s not cheap but it enables me to do maintenance with a fraction of the cost the Subaru representative charged me. Furthermore: every single oil change at the Subaru representative was done using always too much oil, 1 liter or more ABOVE the max mark, and I always would have a bad time explaining I would not leave with the car like that unless they removed the oil in excess. Needless to say they would invent a story on how it was correct, they would correct it after I signed a responsibility notice, and I was billed, very expensively, for all the used oil. I got tired, bought the Select Monitor III, it payed itself with 2 oil changes, never more had to worry about expensive bad service.


  11. In addition to my above comment,my car hasn’t been to a subaru garage for three years and has covered over 20k miles with no reset.
    I have changed the oil myself every 6k and I have had no lights on the dash yet


  12. Hello,
    I have a 2009 2.0D Forester and I’m looking for a way to reset the ”Distance to oil change” counter. I’ve read all your great blog and found that you suggest to use SSM via Serial to reset it. I’ve tried to serial write on the address 0x00029A, that should be the one, but had no success at all… I’m using RomRider to communicate with the ECU via a Tractrix OP2.0….
    Could you please help me? I’d really like to contribute for it! 😉


    • Hi, sorry for the late reply.

      SSM is just a protocol, depending on the actual ROM (the ECU’s software), the SSM write command might or might not actually alter a variable.
      In all Subaru diesel ROMs I have seen, the SSM implementation uses virtual tables. Meaning, based on the SSM address, a specific piece of code is being called. Either to retrieve a (usually scaled) copy of the real RAM variable (getter function) or to do some altering action in case of writes. Writable addresses are rare in any case btw. Think of SSM addresses as sort of IDs, not actual chip memory addresses.
      As in your case, writing to a virtual SSM address often does nothing at all – when no setter function is defined for it. For maintenance operations like oil dilution reset, a series of writes and reads of special addresses must be performed. If done right then this triggers internal code which then (re)set actual RAM variables which, in case of important ones, later get saved into EEPROM at ignition off.

      I might dig up some old notes describing mentioned procedure – within a week or so …


  13. I can confirm that this works on my Australian Delivered 2010 TD Forester Premium. This Was confirmed using snap on solus scan tool. The scanner was connected before the procedure and showed oil dilution of 10%, as the engine was due for a service this was expected but a little surprising, scanner was disconnected without resetting dilution. Service was done and I then did the procedure. Scanner was reconnected and oil dilution was at 0%. I do know of others who have tried this procedure and it has not worked as the ECU has had this reset value locked.


  14. This works on my NZ MY2010/Euro 5 Legacy 2.0D (Yahoo! It works!) – in the manual pp 11-21 & 11-22 with pics. I believe it’s 4 secs per item (“Each step … must be operated within 4 seconds”) but I did the rear fogger-light-repeat thing all in under 4 sec anyway


    • Care about emailing scans or pics of these Euro 5 owner’s manual pages? I’d like to see official instructions and possibly adjust text above. Thanks!


  15. Hi I have just had my 09 Forester (115000kms) blow a con rod or a piston head (second mechanic said not worth the money to investigate but just get a second hand engine) I have had a random diesel guy look at it and he thinks the problem started with DPF system does this seem like a real possibility ?
    if so would this mean that the Subaru service (always serviced at the same place but I was the only diesel they have every seen) didn’t reset the oil calibration?


    • Hi! Not resetting oil dilution won’t do any harm. If estimated dilution reaches 10% you’d get DPF light flashing, trouble code etc.
      Otherwise the ECU does not care, there are no sensors other than oil level switch on Euro 5+ models.
      To get actual oil dilution/quality you’ll need a lab test.


  16. Looks like from the last service they put in 5w30 oil instead of 0w30 as well
    any help would be awesome, thanks 🙂


  17. Worked for me tonight. Changed oil at local garage and today dpf light started flashing. I thought it strange that it went straight to flash without showing a solid light I thought there may be something else.

    I researched and found your page. It seems to have worked and will drive the car tomorrow. Thanks for your information.


  18. I just did the reset on a 2016 outback manual. Definitely worked and the glow plug did fast flash for 5 to 10 seconds then DPF light went out !!!


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.