Hi everyone, once again!

Last year, I bought my first Skoda – an Octavia III 2.0 TDI 184 HP DSG 4x4 with 350,000 km on the clock.
Before that, I had two other VAG group cars – a classic 2001 Audi A3 8L and a 2014 VW Sharan, both diesel.
Despite the mileage, they were absolutely solid. No major issues over the years.

Eventually, I decided to give Skoda a go, and went for this particular spec. Unfortunately, I wasn’t aware of the infamous CUNA and CUPA engine problems at the time.

The car drives great – no performance issues, smooth acceleration etc.

However, I’ve noticed some “abnormal” oil and diesel consumption.
Based on my records, it’s drinking about 1L of oil every 800 km (my lawnmower is more oil-efficient! 😂).
And also while the onboard computer tells me I'm doing 5.5L/100 km of diesel, in reality it’s more like 7.5–8L/100 km.

To make matters worse, I later found out that the previous owner had filled it with 10W40 oil, which I wasn’t aware of when buying the car. I’ve since switched it to the correct 5W30.

I’m 99% sure the oil issue is due to worn piston rings.
But the higher fuel consumption? That one’s a mystery to me.

I had some trouble with the DPF earlier (got the error twice), but after switching the oil and doing some manual DPF regenerations, it seems to be behaving now.

Therefore, I have a few questions for you:

• Do you have any idea what could be causing the high fuel consumption issue?

• Will replacing the piston rings be enough to fix the oil burning problem, or could it be more serious — like needing new pistons as well?

• I'm still unsure about the DPF regeneration interval — does anyone know how to check it?

Would appreciate any insights or similar experiences!

I think more full the DPF is, more the car is consuming. However, I do not believe that is the only reason for such consumption. Perhaps injectors play some role in that too.

If you have VCDS or something equivalent, you cud check injection deviation values. And what comes to dpf intervals, vcds can tell when last regeneration has done and can help in that way. However it is quite easy just to reset the trip meter after regens and follow the intervals "manually".

And with vcds you can check dpf pressure difference to get idea of its health state. Best to check at idle after a regen, below 10 mbar / 10 hpa is OK. Lower the better. Also try to give some throttle while stationary, should stay below 100 mbar at 2500 revs. I am at 10 hpa in idle and the dpf is quite full, regens every 200 km or less if just city driving.

I am consuming 6,4 l/100 km according to the computer and about 7 l/100 km in reality. 250 000 km on the clock.

Edit. I have CUNA also.

Edited 8 May, 20251 yr by Skodaudi

Same car, same engine, 220000km . Fuel consumption - in wintertime around 9L/100km, cold engine and generally shorter trips. In the summer I average a bit over 7L/100km - longer trips improve the average quite a bit. On a longer trip I've averaged below 6L/100km on some B-roads doing 70-90 km/h, doing 130kmh on a highway ups the average by a full litre. Tested on some 300-500km trips.

Oil-wise I guess I'm doing pretty well - a litre per 3000km . Had a small leak from the end of the crankshaft, fixed with the latest beltchange - almost no difference.

On 08/05/2025 at 06:31, Skodaudi said:

I think more full the DPF is, more the car is consuming. However, I do not believe that is the only reason for such consumption. Perhaps injectors play some role in that too.

If you have VCDS or something equivalent, you cud check injection deviation values. And what comes to dpf intervals, vcds can tell when last regeneration has done and can help in that way. However it is quite easy just to reset the trip meter after regens and follow the intervals "manually".

And with vcds you can check dpf pressure difference to get idea of its health state. Best to check at idle after a regen, below 10 mbar / 10 hpa is OK. Lower the better. Also try to give some throttle while stationary, should stay below 100 mbar at 2500 revs. I am at 10 hpa in idle and the dpf is quite full, regens every 200 km or less if just city driving.

I am consuming 6,4 l/100 km according to the computer and about 7 l/100 km in reality. 250 000 km on the clock.

Edit. I have CUNA also.

Unfortunately, I don’t have VCDS, so I’ll have to check around my neighborhood and see if someone can help.

If possible, I’d really like to avoid going down the injector regeneration route... but who knows. First step is to check DPF.

Gotta love the “eco-friendly” solutions in modern cars...

58 minutes ago, Scout_MR said:

Same car, same engine, 220000km . Fuel consumption - in wintertime around 9L/100km, cold engine and generally shorter trips. In the summer I average a bit over 7L/100km - longer trips improve the average quite a bit. On a longer trip I've averaged below 6L/100km on some B-roads doing 70-90 km/h, doing 130kmh on a highway ups the average by a full litre. Tested on some 300-500km trips.

Oil-wise I guess I'm doing pretty well - a litre per 3000km . Had a small leak from the end of the crankshaft, fixed with the latest beltchange - almost no difference.

I’ve been using the car all year round, and in my case, there’s been no noticeable difference in fuel consumption between winter and summer.

About 80% of my driving is on longer trips, typically around 70–80 km, mostly at speeds of 90–100 km/h.
Fuel consumption is based on a distance of 7,000 to 10,000 km, so it's not just a short-term observation.