Oil Level Rising Slowly

Hello,

I'm having a small problem with my 2.0 PD TDI DPF engine. Between service intervals (approximately 20,000 km), the oil level is increasing. Previously, it would decrease (from Max to Min), but now it's rising significantly above Max. Even longer highway drives don't change anything.

Last time, the mechanic checked and, after contacting Audi, received the instructions with some delay on how to replace a few seals on the PD injectors. He also checked the fuel tank to see if oil was being returned through the return line, but found nothing. I also pointed out that the pressure in the crankcase seemed unusually high with the oil filler cap open. The mechanic was also surprised by this, but after comparing it to another vehicle, it seemed more normal to him.

Now I am facing the final inspection before the 100,000-mile mark with the extended warranty, and I want to make sure that there are no issues that will exceed the 100,000-mile limit .

I can imagine the following causes:

"Due to the now higher percentage of biodiesel, more remains in the oil, which only evaporates above 120°C. While I sometimes drive around 160 km/h on the highway for an hour, an average fuel consumption of 7.5 liters per 100 km doesn't necessarily indicate a real thermal stress on the engine."

2. There's still a minor leak at a nozzle, which is so minimal that the amount of fuel being supplied and the amount evaporating into the engine oil is almost balanced (which I find unlikely).

Do you have any other ideas or tests that I can perform, or questions that I can ask my friends?

Thank you!

By how many ml does the oil level increase (after 20,000 km)?
Biodiesel is worth considering, but since the percentage is up to 7% and it was up to 5% last year, I doubt it's that high now...
Aral Ultimate Biodiesel-free? I believe so...
Run motor oil through a cannula (syringe) and measure it with fresh motor oil of the same type and temperature.
Well, I guess there's diesel fuel in the oil... but where does it come from? That's a good question.

scroll tdi wrote:

by how many ml does the oil level increase (at 20000 km)? Biodiesel is worth considering, but since the percentage is up to 7% and it was up to 5% last year, I doubt it's that high now... Aral Ultimate Biodiesel-free? I believe so... Run motor oil through a cannula (syringe) and measure it with fresh motor oil of the same type and temperature. Well, it's estimated that there will be diesel in the oil... but where will it come from? That's a good question

.

Looking at the dipstick isn't entirely reliable. If I assume the difference between the minimum and maximum marks is 1 liter, then there's likely 0.5 to 1 liter too much fluid.

Please check the coolant temperature sensor MWB 007, field 3 (?), with the engine cold.

If there is an upward offset error, the DPF regeneration starts too early (standard = 50°C), causing the late-injected fuel to condense on the cylinder wall and seep into the engine oil. Fossil diesel can be burned off again with a slightly higher load, but unfortunately, biodiesel and its heavier components cannot.

For some vehicles, it may also help to increase the threshold for the minimum coolant temperature required for particulate filter regeneration if fuel contamination problems in the engine oil seem insurmountable. I have experienced this before, and it actually helped .

vwSchrauber wrote:

Please check the coolant temperature sensor MWB 007, field 3(?) when the engine is cold. If there is an upward offset error, the DPF regeneration starts too early (standard = 50°C), causing the late-injected fuel to condense on the cylinder wall and seep into the engine oil. Fossil diesel can be burned off again with a slightly higher load, but unfortunately, biodiesel and its heavier components cannot. For some vehicles, it may also help to increase the threshold for the minimum coolant temperature required for particulate filter regeneration if fuel contamination problems in the engine oil seem insurmountable. I have experienced this before, and it actually helped

.

That's an interesting cause of the error.

Thank you very much, RD.