Hi my Skoda octavia 2016 vrs tdi  auto mpg has dropped significantly from around 460-500 miles per full tank to 300-350

I’ve had the car from 80000 miles , now on 150000 regular services every 100000  but putting oil in every 2-3000 miles now

any help greatly appreciated 

@Mickeyvrs  Do you do short runs where the TDI is not getting up to an efficient oil temp, like maybe under 10 miles from cold starts?

It is winter, is it colder now than when you were getting 460-500 miles?

 

When was the Air Filter checked and do you adjust tyre pressures as the ambient temperature changes?

 

PS

With a Full Tank do you mean you fill up with like 10 gallons / 45.5 litres. because 460-500 is not great in 50 litres? 

This is obviously worrying.  I suppose we really need a couple of things (of information).

 

1) What type of journeys do you do?  Long or short - are you a progressive or eco-warrier in terms of your driving style

2) When was the car last serviced?

3) When you say you put in oil every 2-3000 miles, how much oil and what type of oil are you using?

 

Things to check:

 

a) Fuel Injectors - they tend to get a bit dodgy after 120,000 miles.

b) DPF - my biggest concern is that you may have a block DPF.  When was the last time your car did a full/long/hard regen?

 

Can you either invest (or go find somebody with) - either a genuine VCDS or ODBEleven scanner - get a scan done and post it here pls?

3 minutes ago, Ootohere said:

@Mickeyvrs  Do you do short runs where the TDI is not getting up to an efficient oil temp, like maybe under 10 miles from cold starts?

It is winter, is it colder now than when you were getting 460-500 miles?

 

When was the Air Filter checked and do you adjust tyre pressures as the ambient temperature changes?

 

PS

With a Full Tank do you mean you fill up with like 10 gallons / 45.5 litres. because 460-500 is not great in 50 litres? 

My tank is 45 litres ,  car was serviced 3 months ago with new air filter and oil already put approx 3 litres of oil in last week , as for runs I drive 60 miles a day for work (300 per week all motorway ) and maybe 60 miles urban driving at weekends ,tyres are just generally at normal levels 40 psi I think , it’s 

winter now but problem arose in summer months. Car is driven sensibly in eco mode and no signs of oil leakage 

3 litres of oil just last week, or since the service?

 

Are you sure enough oil was in from the service? 

 

A 50 Litre fuel tank and it holds more than that up the tube.

A Fabia has a 45 litre tank.

Edited 15 December, 20241 yr by Ootohere

33 minutes ago, Ootohere said:

3 litres of oil just last week, or since the service?

 

Are you sure enough oil was in from the service? 

 

A 50 Litre fuel tank and it holds more than that up the tube.

A Fabia has a 45 litre tank.

I’ve had the oil problem prior to the service , oil light coming on every 2000 miles or so , oil was changed and filled at service and 3 litres added since the service 3 weeks ago so 9-10 weeks until low oil warning came on. I’m assuming my tank is 45 litres as that what it takes to fill can get 46 litres in at a push 

More important to sort the Oil excessive consumption then since 3 litres of oil costs more than 2 gallons of diesel. 

Edited 15 December, 20241 yr by Ootohere

22 minutes ago, Ootohere said:

More important to sort the Oil excessive consumption then since 3 litres of oil costs more than 2 gallons of diesel. 

Any ideas of why it’s using so much oil ?

How often is it calling (and completing) a DPF regen?

24 minutes ago, Warrior193 said:

How often is it calling (and completing) a DPF regen?

It’s not as far as I know 

Are you saying that DPF regens are not occurring at all?

Just now, Warrior193 said:

Are you saying that DPF regens are not occurring at all?

Don’t want to sound like an imbecile but how do I know if they are ?

I don't drive a diesel, but there should be a yellow symbol lit up in the instrument cluster (apparently looks like an exhaust silencer) when a regen is called for - this warning light might be accompanied by the MIL light if there are issues, there will also be a warning text message if the regen is interrupted before it is completed.

Just now, Warrior193 said:

I don't drive a diesel, but there should be a yellow symbol lit up in the instrument cluster (apparently looks like an exhaust silencer) when a regen is called for - this warning light might be accompanied by the MIL light if there are issues, there will also be a warning text message if the regen is interrupted before it is completed.

Thought as much no warnings or lights to suggest this maybe the mileage has took its toll it still drives perfectly just not as economical as it was 

All warning lights should light up during switch on, start up test - does the DPF warning light up then? Have you ever seen this warning indicator in the time you've owned the vehicle?

It is possible that the DPF has been 'gutted' or otherwise tampered with before you purchased it. 

 

13 minutes ago, Warrior193 said:

All warning lights should light up during switch on, start up test - does the DPF warning light up then? Have you ever seen this warning indicator in the time you've owned the vehicle?

It is possible that the DPF has been 'gutted' or otherwise tampered with before you purchased it. 

 

Had the car for 5 years no indication of dpf problem and has ran sweet until recently , had a Saab a few years ago with dpf problem and I knew all about it , black smoke poor performance etc as well as warnings from the car itself 

If regens happen normally there are no lights in the dash. DPF warning light comes on only when there are issues with regens. Basically it is made to be as unnoticiable as possible by Skoda.

 

However, during active regen, while stopping ie. at traffic lights one might notice higher idle revs and possibly smell something is burning. Also in city driving higher revs / lower gears overall can be noticed  And if you shut off the engine during active regen, the fan will stay on for some time and it smells like burning.

 

Besides active regens, also passive regen happens during motorway driving, basically high enough load provides high enough temperature for some particle burning. With your driving, less active regens are needed.

 

If the engine burns oil, dpf will suffer and needs more regens.

 

Mpg drop and oil consumption together sound bad. Piston or piston ring problems perhaps? Low compression pressures due to piston (ring) damage would explain low mpg and how oil is burning. I hope this is not the case.

 

Have you had fault codes read? There might be something pointing to right direction.

Edited 15 December, 20241 yr by RattleWagon

2 hours ago, Warrior193 said:

All warning lights should light up during switch on, start up test - does the DPF warning light up then? Have you ever seen this warning indicator in the time you've owned the vehicle?

It is possible that the DPF has been 'gutted' or otherwise tampered with before you purchased it. 

 

 

19 minutes ago, RattleWagon said:

If regens happen normally there are no lights in the dash. DPF warning light comes on only when there are issues with regens. Basically it is made to be as unnoticiable as possible by Skoda.

 

However, during active regen, while stopping ie. at traffic lights one might notice higher idle revs and possibly smell something is burning. Also in city driving higher revs / lower gears overall can be noticed  And if you shut off the engine during active regen, the fan will stay on for some time and it smells like burning.

 

Besides active regens, also passive regen happens during motorway driving, basically high enough load provides high enough temperature for some particle burning. With your driving, less active regens are needed.

 

If the engine burns oil, dpf will suffer and needs more regens.

 

Mpg drop and oil consumption together sound bad. Piston or piston ring problems perhaps? Low compression pressures due to piston (ring) damage would explain low mpg and how oil is burning. I hope this is not the case.

 

Have you had fault codes read? There might be something pointing to right direction.

Thanks mate nothing showing on fault code when serviced ( only an ac problem detected)

 Hope it’s not the pistons !

 

 

Excessive oil comsumption is usually two things on VAG cars:

 

1) Piston rings are worn / sticking and potentially if the car has lacked maintainance, then cylinder scoring is fairly terminal (unless you get the cylinder liners redone).  Lets hope not.

2) Cylinder Head Gasket has failed - however, this will also cause pressurisation in the coolant system.  Quick test - start the car and open up the lid of the coolant tank (when the car is cool otherwise scolding will occur) and see if there is pressure being pushed into the coolant tank (a good indicator will be bubbles in the coolant header tank).  If so, highly likely the cylinder head gasket has failed.

 

In all this, its REALLY important that you get this sorted above everything else.  Otherwise you will just end up with a block DPF and a broken engine.

Edited 16 December, 20241 yr by varaderoguy

18 hours ago, Mickeyvrs said:

I’m assuming my tank is 45 litres as that what it takes to fill can get 46 litres in at a push 

 

Thats because you are believing the kidology telling you the tank is close to empty with zero miles remaining, you in fact have another 7 litres of reserve capacity for the day you really need it.

 

That said it wont affect your observations about reduced range as you are consistently filling up with the same amount of fuel.

A possible check would be to check the tail pipe of your exhaust with your finger for oil. There shouldn't be any.