DPF and Oil Dilution Issues

[Duffsaw]

Evening All,

Firstly, i realize this issue gets ran over a good few times here, but I still haven't managed to glean the info I was hoping for.

So, if you will suffer my questions, I would appreciate your advice and experience.

I have a 2012 2ltr turbo diesel Forester, 233000km, here in Ireland. Well maintained, more by myself now, as she gets older, and less valuable. At present, my plan is to keep her, until she leaves me, in pieces... I love it!

She has been very reliable, and runs great, no issues, until this popped up recently.

In June, i had the DPF light come on. I done a small bit of research, and rather than start messing about, I thought as it was her first time showing this, it was likely genuine, and called the lads in the local Subaru dealership. Good Lads to be fair. They found the fault was oil dilution, and the car needed a Regen. They carried this out, but explained, as i was now servicing myself, i hadn't been resetting the oil change counter, and said it needed a computer reset anyway. I was unaware this needed to be done. Anyway, the oil level was very high, and as they were slotting me in between people to help me out, they just dropped some out, and said i should change oil myself at next opportunity, which I did on the following weekend. All good so.

But only 6 weeks later and about 2-3000km only, the DPF light comes on again, for a couple of days, then goes out for a couple more, then comes on again, and stays on. I called the guys again, who dutifully, slipped me in, checked it out, oil dilution again, not soot, and reset it for me. Told me to check oil level, and it is again high, and I will need to lower/change it again.

At this point, I asked about removing the DPF, if that is the route cause, and not completing regen's, thus dumping fuel into the oil, unsuccessfully. They said it can work, by drilling out the DPF, as replacement is very costly. But will this stop the system/ECU dumping fuel into the oil to do a Regen, or will this carry on? I suppose my question is, does anyone know what ACTUALLY triggers the fuel getting dropped into the oil, and will removal of the DPF stop this problem from occurring into the future?

[Mr B]

the ecu assumes regen is needed by measuring back pressure which gets higher the more soot the dpf is holding, then when it decides regen it adding more fuel to heat the dpf to burn out the soot.

DPF systems is an awful engineering concept and does nothing for environment as the system ruined diesel mpg economy and it wastes even more fuel and oil with regens !

With mileage you done DPF highly likely need replacing, you could try special cleaning but you be wiser spending on a top quality aftermarket dpf and at a independent garage as dealers be silly money on this job, you may even find oem dpf at better cost outside a dealership .

Before jumping on the DPF you ideally want back pressure monitored to concluded DPF is too restrictive .

You are right that if DPF is sorted then regen and oil dilution should be rectified but that assumes all else is working correct and DPF health is falling below functional level and this really needs be concluded to move forward with repair option .

serious repetitive oil dilution is pretty serious issue and 1 reason towards the all too common crank failure .

[Duffsaw]

Great info Mr B, and thanks for the reply. I will investigate the soot on DPF so at earliest opportunity

[Duffsaw]

Hi All,

This issue has raised its head again. After only another short period. I am seriously thinking of removing the DPF and getting the ECU remapped. Has anyone done this? Any recommendations either way from anyone, whether to do it or not?

BTW, I am also looking into changing the wheels, and maybe changing some trim like the front grill etc. Any recommendations of good sites for gear, maybe even chip guards for the bonnet... Like the look some of the off road community on YouTube have for their forester's. And i want to keep her now, as wouldn't get a lot for her in a trade in anyway.

[MelissaH]

On 10/25/2020 at 5:53 AM, Duffsaw said:

Hi All,

This issue has raised its head again. After only another short period. I am seriously thinking of removing the DPF and getting the ECU remapped. Has anyone done this? Any recommendations either way from anyone, whether to do it or not?

BTW, I am also looking into changing the wheels, and maybe changing some trim like the front grill etc. Any recommendations of good sites for gear, maybe even chip guards for the bonnet... Like the look some of the off road community on YouTube have for their forester's. And i want to keep her now, as wouldn't get a lot for her in a trade in anyway.

What did you end up doing with this problem? We are going through the same thing! 😫

[Duffsaw]

Hi Melissa,

Sorry to hear of your troubles. But it can be sorted. I got a company here to remove the DPF and remap the system to take account of the removal, and thus no need for burns and dropping fuel anywhere etc. It has worked great for me, in that the problem is sorted, at a reasonable cost. no loss of power or performance issues. All good so far. I keep her serviced very regularly, and she is back to be the reliable fun car it had been up to that point.

Hope this helps

[Judd]

Don't blame you for the solution Duffsaw, but not the ideal solution for the UK because MOT inspectors are hot on DPF removal (even if the now gutted canister remains in place) and i'm sure there's insurance implications too.

You won't get any stick from me because DPF is a pita in cars and domestic 4x4s, in lorries they've got it pretty well sorted unless the vehicle is on short haul multi drop work, even then the latest vehicles are fitted with switching so the driver can regen on command whilst stationary if the vehicle needs it and the type of running won't allow a normal regen on the move.

[Mr B]

worse case is nasty court hearing and fine and car in a crusher .
Done right it hard for MOT inspector know but MOT test changes are likely in emission equipment unfortunately
DPF and EGR systems are such a poor concept huge amount have bypassed them and that made a lot of companies unhappy, they want your money, no real care about pollution that just an excuse to sell lesser quality and engineer systems that cost you more money maintain and more garbage for landfill .
About time consumers got wise and stopped buying new junk ...