So my fiesta has an ongoing issue where the oil level keeps rising.

Main dealer has had it twice and just said their technician has overfilled the oil by accident when they serviced it! Really?!! (I had no choice but to use them as it was leased at the time, but since bought by me)

took it to my trusted local Indy today and he says the dpf regen is working, it regenned this week and has 40% soot, there are NO dpf errors.

he also said that it’s showing some weird things,

engine coolant showing -40 degrees 

oil temp sensor and exhaust pressure sensor have both showing no readings as if they’re disconnected but not throwing any error codes either 🤷‍♂️

im going to take it to another main dealer but not the original one as I’ve lost trust in them but just wondering if anyone has any ideas or has maybe experienced similar issues?

Even completed regens dump some diesel into the oil.  It's pretty standard on any car with a post injection regen.  How much excess are you getting and over how much time?

Injector leaky?

4 hours ago, TomsFocus said:

Even completed regens dump some diesel into the oil.  It's pretty standard on any car with a post injection regen.  How much excess are you getting and over how much time?

 

Only 2500 since last service (54k) and oil level is showing over Max on dipstick, it’s being constantly doing this for 12 months. Ford say they can’t find anything (other than their techs don’t know how to fill the oil) 

never had any warning lights connected to contaminated oil, just that oil needs changing

 

I don’t claim to be an expert on this. I thought the main cause of this is if you turn off the engine when it’s part way through a regen. I know it does not tell you this on the dash. I think if you turn off and the radiator fan continues flat out is a sign

8 hours ago, Johntyburger said:

Only 2500 since last service (54k) and oil level is showing over Max on dipstick, it’s being constantly doing this for 12 months. Ford say they can’t find anything (other than their techs don’t know how to fill the oil) 

never had any warning lights connected to contaminated oil, just that oil needs changing

If you're doing a lot of short journeys you're probably failing regens without noticing.  I can fail 3 or 4 in a row just driving locally without any warning lights or problems, it'll eventually complete one next I do a longer drive.  I only fill the oil to half way between max & min to allow for the level rise before the next service.  It's always over the max mark by the service.  I've had this on both Fords and VWs with this type of DPF.  

 

1 hour ago, isetta said:

I don’t claim to be an expert on this. I thought the main cause of this is if you turn off the engine when it’s part way through a regen. I know it does not tell you this on the dash. I think if you turn off and the radiator fan continues flat out is a sign

There's so much excess diesel dumped in during post injections that some will always pass the rings as blowby.  The main problem with failing them is that that process is repeated until it passes one rather than being a problem in itself.  The other issue is prolonging regens in slow or stop start traffic.  The quicker you can complete one the better.  So while they will regen around town now, it's still better to do a motorway regen.

Mechanic has confirmed that regen is working as it should and system hasn’t shown up any failed regens 

39 minutes ago, Johntyburger said:

Mechanic has confirmed that regen is working as it should and system hasn’t shown up any failed regens 

As stated in some of the comments, a successful Regen will result in some fuel getting into the oil and if the car is used for a lot of short journeys then it will regenerate more and some of them will not be complete when stopping the car as well.

Your mechanic may be correct, the system is working as it should, that does not mean that you will not get a lot of Diesel in your oil. 

We’re all in agreement about how the dpf works, regens etc BUT what about the -40 reading on the coolant sensor and the oil pressure and exhaust pressure sensors not showing any readings as if theyre disconnected (but not showing error codes)?

 

1 minute ago, Johntyburger said:

We’re all in agreement about how the dpf works, regens etc BUT what about the -40 reading on the coolant sensor and the oil pressure and exhaust pressure sensors not showing any readings as if theyre disconnected (but not showing error codes)?

Probably just caused by non genuine diag equipment.  Does the dash show normal coolant temp when you're driving?

If these things were not working you would have a Christmas tree of warning lights and malfunction messages in the display. The car would almost certainly be in limp mode, too, particularly in the case of the dpf pressure sensor.

I know the comment below isn’t Ford specific;

With BMW Diesel engines, at the time of service the oil is only replenished to 3/4 full to allow for dilution from regen cycles. So the oil level increasing due to diesel pollution isn’t wholly abnormal.

Going back to when I used to run a couple of Fiesta 1.6 TDCi 2011 and 2014MY they always had a good run to London and back at least once a week and I never saw the oil level increase. I think that’s the main thing with diesel technology these days they need exposure to motorway driving on a regular basis.