2013 B8.5 S4 oil consumption issues

[STW]

Hi everyone looking for some thoughts on an issue I've been having for some months now re oil consumption on my S4.

I purchased 2013 B8.5 S4 in June 2022. It had 88k on the clock and had been serviced at the garage I purchased it from for the past 5 years and has FSH. Everything was fine with it then in Nov 22 the minimum engine oil warning light came on and it was topped up by the garage I bought car from as a couple of minor issues were being fixed under the 6 month warranty.

Since Nov 22 I've had to top up oil about 5 or 6 times. Its been back at the garage I bought it from who confirmed no oil leaks on the 2 separate occasion's they have looked at, last time April 23 when it was getting main service which included new spark plugs installed, and nor are there any puddles of oil on my drive way (which is on a slight slope in case thats relevant).

The car will hit the 100k mile mark this week and I've just put another litre of oil in about 600 miles after the last lot. The oil I've been using is Comma Pro1 Prolife fully synthetic 5w 30 which seems to be fine for Audis according to garage that sold me it. When the minimum engine oil warning light comes on, if I open and close the bonnet without adding any oil then the light goes off for maybe 100-200 miles before coming back so wondering could it be a faulty sensor somewhere?

Any other idea what could be causing this issue and how concerned should I be about it? The garage seem to think that as its a larger 3 litre V6 engine (previous largest engine id had was 2.0 TDI A4) then it will go through more oil and didnt seem overly concerned about this. However I'll stress i'm not mechanically minded at all but this didnt sound right to me but happy to be corrected if anyone thinks this could be the case?

Given my lack of mechanical knowledge and not getting far with the garage, a spot of googling has led me to think it could be one of the following (although Id have hope the garage would have eliminated these on one of the instances they were checking the issue) -

Piston rings issue/ piston con rod issue. If its one of these then I'm assuming that's expensive to establish and then fix?
Leak in coolant
Water pump issue - positive the service history shows this was replaced around the 75k mark though
Oil pump filter issue
Faulty sensor somewhere

I've noticed there is a 40 page thread on this sub forum started in 2015 regarding oil consumption in 2009 - 2011 models so any chance it could be related to this?

Any thoughts and advice greatly appreciated before I go back to garage and get them to check for things that potentially could be expensive but not help me solve the problem. Or is it the case that given mileage and engine size of car then this is actually normal? Unlikely I know....

Thanks in advance

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[ninjag]

I've read that the PCV valve can cause this. Mine drinks a little oil, seems to be a sporadic drop rather than a gradual reduction. I changed the oil 2 1/2 weeks ago, filled it to about half way between the lines and two days ago I had to top up. It will probably go for a while now without needing any more and then out of the blue... lol

It's a little inconvenient, but I'm not particularly worried as there are no leaks and every works great. My code reader shows an intermittent log for the PCV valve so I'm keeping my eye on it. Also a B8.5.

 

[STW]

Hi and thanks for the reply.

PCV valve wasn't something I had came across on my googling so will be something I'll mention to garage. Its just really odd that if I open and close the bonnet the oil light goes off for a while. Frustrating that these cars don't have dip stick either to actually check the levels manually rather than rely on computer as even after I've put a litre of oil in, it barely seems to move the gauge when checking it via the onboard system

 

[Dippy]

PCV is the main cause of oil consumption on this engine. When you have topped up, how much effort was it to remove the fill cap? A bad PCV can create quite a vacuum.
It is possible to get a dipstick which fits this engine (although there isn't one specifically for it). I don't recall the part number but it will be in a forum somewhere.
Have you checked for signs of oil in the coolant and vice-versa?

 

[Dippy]

BTW whilst some oil consumption can be considered normal, frequent filling is not. The only time oil goes into my engine is at the annual service.

 

[STW]

Thanks Dippy

Fill cap comes off fairly easily without too much effort whilst car is sitting cold however just tried it there with the engine idling in the driveway and whilst the cap screwed off ok, to try and remove it did create a bit of a vacuum and hissing sound when trying to take it fully off. I've not checked for oil in the coolant or vice versa but going to mention this to garage when getting them to look at PCV

Many thanks for the reply

 

[Dippy]

If it is a bad PCV then the supercharger needs to be removed to replace it. Other items which could be replaced at the same time are the waterpump and thermostat. Both are items that can leak and/or cause problems at higher mileage. Then there's the crank pulley and tensioner. The former has a polymer dampening material that can crack at higher mileage. Service position is needed for a proper inspection but that's not really difficult for a tech to do.

 

[STW]

If it is a bad PCV then the supercharger needs to be removed to replace it. Other items which could be replaced at the same time are the waterpump and thermostat. Both are items that can leak and/or cause problems at higher mileage. Then there's the crank pulley and tensioner. The former has a polymer dampening material that can crack at higher mileage. Service position is needed for a proper inspection but that's not really difficult for a tech to do.

Thank you again - I shall mention all these things to the tech when car goes in next week so shall see what they say. Already sounds expensive

 

[JohnS3]

The dipstick part number is 06E115611H

 

[g00se]

Crank pulley failure is a good excuse to get a billet single piece version and go stage 2 - that's what i did lol!

As for water pump, thermostat and PCV, budget circa a grand.. that's what Awesome have quoted me, and mines going in mid-Sept. Mines a 2014 with 74k... PCV's can start to fail anywhere between 60-100k. I've had mine for a couple of years and done 20k, but the last few months the oil usage has increased slightly, and as Dippy says, the oil cap is being sucked on when idling, so time to get it done for piece of mind.

I also considered getting the intake valves walnut blasted too whilst the blower is off.. however Awesome have said they would then need the car for 2 days which is no good for me as its my daily... so that job will have to wait.

I will however get the weak plastic supercharger bleed screws swapped out for the ECS billet ali screws... as they are yet another common failure item

Cheers
goose

 

[Dippy]

I also considered getting the intake valves walnut blasted too whilst the blower is off..

Yours is a 2014 build car? Did it get the CREC engine? If so it appears that the injectors are keeping carbon build-up low and cleaning is not needed.

 

[g00se]

Sadly not, i believe mine to be an early 2014 non-CREC motor so a carbon de-coke is on the agenda.. it may just have to wait till funds allow.

goose

 

[ninjag]

I quickly checked my oil cap last night with a hot engine and there's a fair amount of vacuum, so will need to check codes again as I do have an intermittent PCV valve code. Could do without a PCV valve change at the moment as have a lot on. I'm still not 100% convinced as there's conflicting info online, with some saying oil cap vacuum is normal with modern engines.

 

[Ajwhite]

I quickly checked my oil cap last night with a hot engine and there's a fair amount of vacuum, so will need to check codes again as I do have an intermittent PCV valve code. Could do without a PCV valve change at the moment as have a lot on. I'm still not 100% convinced as there's conflicting info online, with some saying oil cap vacuum is normal with modern engines.

I had this exact issue. oil consumption, vacuum on the cap, subtle lumpy idle.

I'm now £800 lighter but cars running fine with no oil consumption in the past 200 miles

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[ninjag]

I had this exact issue. oil consumption, vacuum on the cap, subtle lumpy idle.

I'm now £800 lighter but cars running fine with no oil consumption in the past 200 miles

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Cheers, I'm guessing you got the pcv valve replaced?

At the moment I'm not fully convinced with regard to mine as I'm reading different things from a variety of sources with some saying that it's normal to have as little suction with these engines.

I have some suction, when I remove the cap the revs increase a little then fall and fluctuate slightly. I'm not losing coolant, my fuel trims are perfect and after doing an oil change the old oil looked fine.

I've had to top up once not long after doing the oil change, but since then it's been fine. I have had a very infrequent and intermittent code ping up for the pcv valve, but when cleared it doesn't come back for ages.

I might let things develop.

 

[Ajwhite]

Cheers, I'm guessing you got the pcv valve replaced?

At the moment I'm not fully convinced with regard to mine as I'm reading different things from a variety of sources with some saying that it's normal to have as little suction with these engines.

I have some suction, when I remove the cap the revs increase a little then fall and fluctuate slightly. I'm not losing coolant, my fuel trims are perfect and after doing an oil change the old oil looked fine.

I've had to top up once not long after doing the oil change, but since then it's been fine. I have had a very infrequent and intermittent code ping up for the pcv valve, but when cleared it doesn't come back for ages.

I might let things develop.

I did get the PCV replaced about 600 miles ago, although ive now noticed the same symptoms, oil consumption and vacuum on the oil cap again so I'm a bit stumped

I'm thinking the parts failed but I'll keep you posted if its something else, could help.

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[ninjag]

I did get the PCV replaced about 600 miles ago, although ive now noticed the same symptoms, oil consumption and vacuum on the oil cap again so I'm a bit stumped

I'm thinking the parts failed but I'll keep you posted if its something else, could help.

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That's worrying, this is what's making me hesitant to change mine. Can the old PCV valve be physically checked on the bench somehow? I wonder what else your could be - how are your fuel trims?

I would have thought checking the intake manifold pressure could be a good indication of a failing PCV valve, but I don't know what the normal readings should be.

 

[Ajwhite]

That's worrying, this is what's making me hesitant to change mine. Can the old PCV valve be physically checked on the bench somehow? I wonder what else your could be - how are your fuel trims?

I would have thought checking the intake manifold pressure could be a good indication of a failing PCV valve, but I don't know what the normal readings should be.

Not sure if it can, you can by the valves and springs separately so not sure if that what's happened and the part has failed elsewhere.

They garage is usually pretty good, so would have thought the part would be replaced entirely? Also heard some stuff about pipework to/from PCV failing causing it to consume oil but not leak etc.

Booked in beginning of October so will update on what they find.

Just another £££

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[ninjag]

Not sure if it can, you can by the valves and springs separately so not sure if that what's happened and the part has failed elsewhere.

They garage is usually pretty good, so would have thought the part would be replaced entirely? Also heard some stuff about pipework to/from PCV failing causing it to consume oil but not leak etc.

Booked in beginning of October so will update on what they find.

Just another £££

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I didn't think they were serviceable and had to be replaced? Could be wrong, but if it were me I would replace.

I think there are coolant pipes integrated into it (insane?) and these can leak and contaminate the oil; I'm sure I've seen a video showing this. I also think the B8.5 one operates to lower pressure than the B8 (would need to check this), so important to make sure the correct part is used?

Do you have the PCV valve fault code coming up in a scanner?

 

[Ajwhite]

I didn't think they were serviceable and had to be replaced? Could be wrong, but if it were me I would replace.

I think there are coolant pipes integrated into it (insane?) and these can leak and contaminate the oil; I'm sure I've seen a video showing this. I also think the B8.5 one operates to lower pressure than the B8 (would need to check this), so important to make sure the correct part is used?

Do you have the PCV valve fault code coming up in a scanner?

Yeah, there are definitely coolant and oil pipes I think attached somehow

I don't have a scanner but previously it was coming up from what I was told. Be interesting to see if it's coming up again.

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[Ajwhite]

I didn't think they were serviceable and had to be replaced? Could be wrong, but if it were me I would replace.

I think there are coolant pipes integrated into it (insane?) and these can leak and contaminate the oil; I'm sure I've seen a video showing this. I also think the B8.5 one operates to lower pressure than the B8 (would need to check this), so important to make sure the correct part is used?

Do you have the PCV valve fault code coming up in a scanner?

So, good news!

PCV isn't showing any codes or related codes at all. All seems to be fine and I'm consuming a tiny bit of oil per 1k

I was being a hypochondriac about it haha

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