Quart of oil burned in a day

[S4Kev]

I have a 2008 s4 with 76k miles and a couple months back my oil min light came on so I filled it up and ever since then the light would come back faster and faster, its at the point where I'm putting in a quart every five days because the light keeps coming back. So Saturday morning the light came on when I started the car to go home from the beach which is 60 miles from my home all highway,I poured a quart and drove home. And then I did some local driving, maybe about 20 miles. Sunday afternoon after running a couple errands I did maybe another 25 and the light came back on. So pretty much I barely did 100 miles and I burned that quart in less then a day. I would greatly appreciate if I could be guided towards what I should look for on my motor and where so I can go about fixing this mess. Thank you

[Lucca M]

Check your compression and boroscope cylinders. Is it leaking oil?

[S4Kev]

My valve covers are a little wet on the bottom but I doubt I'd lose a quart in a day from that,another thing is, if I let the car cool down for about 45 minutes after its fully warmed up,when I start it, it puffs smoke like a chimney and it smells terrible. If that helps

[jakeoboy67]

if it's burning that much oil, there has to be one hell of a blue smoke cloud behind you

I'd check for leaks ASAP

when the oil light comes on, do you manually check the oil(with the dipstick) before putting some in ?

[S4Kev]

when the light comes on and I check the dipstick there is barely any oil on it,just right on the tip

[jakeoboy67]

when the light comes on and I check the dipstick there is barely any oil on it,just right on the tip

this confirms that you oil level sensor works good !
any puddle under the car ? (do you still have the OEM belly pan/skidplate ? )

[S4Kev]

Yes I still have it on, I think I'll take it off tomorrow and clean up the motor,then let it run for a bit and see if I can see anything,if not then I am completely stumped. The only thing is that when the engine is still kind of warm and I start it,it smokes heavily for about 10 seconds and it smells like a mixture of burnt coolant and plastic

[SuperAvant]

When is the last time you changed your oil?

[kevinye77137]

Check or replace pcv valve and see if that makes a difference

[verymickey]

Check or replace pcv valve and see if that makes a difference

when you say 'check the pcv valve' what are you checking for exactly? oil in the area? worn hoses? cracks?

[kevinye77137]

Sometimes the pcv valve gets gummed up with a whitish brown sludge and cause it to clog or stuck open. Check for that and try sucking and blowing from one of the hole. If you dont notice anything different when blowing and suck.. hehehe.. then you got a problem. When clogged your blow by Gases can't be sucked back into the intake manifold causing pressure in the crankcase. This will cause oil to be pushed out through gaskets. When stuck open the vacuum from intake manifold will suck in oil and burned in the combustion cycle. Correct me if I'm wrong fellow audiziners :)

[emilio]

i would be extremely amazed if a bad PCV or even scored cylinder walls caused the loss of a whole quart of oil in a day of normal driving. maybe if you drove 1000 miles in that day, sure, but just around the area? to go through oil that quickly in 100 miles i would expect a big leak, some nearly-destroyed piston rings and possibly related cylinder wall damage (more than scoring), or a severely malfunctioning PCV system (not just the valve).

is there a CEL? can you pull DTCs? does the engine otherwise run and drive as normal?

also, keep in mind that the oil level light comes on when you need 1.5-2 quarts, not 1. with the engine warm, the tip of the dipstick is about 1.5qt to the top of the measurement marks.

- emilio

[Aok303]

when you check the dip stick does it smell sweet?
a bad pvc would take more then 100 miles to burn that ]
and to burn it through the back you would have to be smoking like a smoke stack on a coal plant. you would constant see some smoke
does it smoke any in the engine bay or just out you tail pipes

[SuperAvant]

In all my time researching this issue though I've never seen the culprit be a bad pcv.

[vailshred]

Smoke after a car sits is usually caused by the valves leaking. The oil seeps into the cylinders through the valve and then when the car is started the oil smokes as it's being burned.
First thing I would do is compression and leak down tests. This will give you a idea of where the oil might be going. The fact that is smokes after sitting for a bit is proof that the valves are definitely leaking.

Please let us know what you find out and good luck

[badger.]

I've never found a clear answer either.

I regularly make trips to Michigan (~300 miles one way). Most recently this past weekend:
Topped off oil/fluids before the trip
Drove up
Check the oil upon arrival (couple hours after)
Was 1.5-2 qts gone
Filled it back up
Drove home a day and a half later
Maybe about 1/4 qt low
.....


I drive ~75 miles a day for work. I check my oil every weekend. Sometime I add 1qt or more. Sometimes I add nothing.
PCV is new (twice)
No oil leaks on the ground (coolant and PS fluid but not oil! lol)
I drive the same route, speeds, etc...
Never notice large clouds of smoke, maybe a bit on cold starts
Exhaust tips and rear bumper get all sorts of fun specks and oily film over the weeks... I'm assuming it is from the exhaust
Compression #s are solid for having 187k miles on the car (135-150)

My only conclusion is there is very little rhyme or reason to my oil consumption? magical disappearance? burning? I don't know. I suspect it is some fickle combination of weather, driving habits, cylinder scoring, and valve stem seals. But no idea for sure.

[jmcS4]

^^^^ i'd say 135psi for compression numbers are on the low side. it seems the cutoff for acceptable numbers in 140 and above. only a 5psi difference but different none the less

[GaretS4]

Unless you know the complete background of your engines' maintenance history (including frequency and specifications of oil used) and the previous owner's driving style, I wouldn't rule out excessive engine wear with oil getting past the rings and valve guides. This engine has 32 valve guides which is a lot of potential entry points. Engine wear can be accelerated by both infrequent oil changes, using the incorrect weight for the season, or using the incorrect grade of oil, and increased engine loads. There are a series of tests that can be performed to determine wear location. That said, even when you do everything right and your engine is in prime condition, these engines will use oil when pushed hard. So lets consider the oil in your crankcase and ones' driving style to see how they impact oil consumption.

1. The oil factor. There are huge differences between the breakdown rates and volatility (evaporation) of the various engine oils. Oil can shear and split into smaller length molecule. High engine loads lead to greater sheer forces. Lighter weight oils (as used for winter conditions) have more smaller oil molecules which can move past tighter spaces such as rings, guides, and seals. Engine tolerances also change as the engine heats up. Some spaces close up whereas others may increase. Smaller molecules also tend to be more volatile and will move out through the crankcase vent or seals. Synthetic oils tend to a greater resistance to shear forces and have lower volatility, though not all are equal. A bit of internet searching of oil brands led me to Amsoil's site where they actually provide volatility, high temp /high shear viscosity, and wear ball test results. I haven't found similar test results from the other brands, but I'll keep looking. Note that these engines require AECA A3/B4 rated oil which are full SAPS and and designed for added wear protection. Anything else is a disaster in the making. Do you have a oil change/grade history of the car?

2. The driver factor. Higher engine revs and increased engine load from fast acceleration or higher road speeds leads to higher engine temps and pressures. This results in greater oil sheering force leading to smaller oil molecules, which combined with higher temps leads to a thinner oil, increased volatilization losses, and/or slippage past the rings and guides.

Using my car as an example, it's a low milage (40K miles), recently acquired 05 S4 with a maintenance history going back 6 years. Oil changes were frequent and well within the manufactures specs. Oil grade was correct except for one instance when they did not use an ACEA A3/B4 grade. The car came with a fresh oil change which was Castrol Edge European Formula with SPT 0W-30 (ACEA A3/B4). I live in northern Canada so the oils weight was acceptable for winter driving. Initially I drove the car gingerly and saw only minimal oil consumption; the equivalent of a quart in 2-3 thousand miles. As I got to know the car I began to push it harder using more of the engines upper rev range, accelerating quicker, and use the engine's compression for braking. I then noticed an increase in oil consumption at about a quart in 400-500 miles. I recently made a trip to the rocky mountains and did some spirited driving on isolated secondary roads having steeper grades and lots of switchbacks, meaning lots of gear changes and acceleration bursts. It was a great drive but in one afternoon the engine used 1 quart in about 200 miles. I was a bit shocked to say the least, but I shouldn't have been surprised what with pushing the engine hard and 0W-30 oil weight in the crankcase. This spring I changed to Castrol Edge EU Formula 0W-40 and after 3000 miles consisting of a road trip of 800 miles, several 200 mile trips plus around town driving the oil level has hardly moved on the dipstick. I haven't done any hard charging since the trip to the mountains so can't say what the impact of that sort of drive would be on consumption, but I'm sure there would be some. For comparison,I also have a 96 SL500 that has an aluminum cylinder block that I believe uses the same technology as Audi for hardening the cylinder wall. One thing I came across in the Mercedes owner's manual is the importance of checking the oil level after spirited driving and after high speed motoring as oil consumption will be increased. I find the SL's oil consumption to be minimal, though it is only a summer driver and gets Mobil One's European Formula 0W-40 (ACEA A3/B4 as specified by manufacturer). The SL's engine doesn't rev as high as the S4, has taller gearing, plus it has an automatic transmission, which is great for loafing around town or cruising on the highway, but doesn't inspire one to the same degree of spirited driving as the S4.

I hope you are able to identify the source of your engines' excessive oil consumption and it's nothing to serious.
Garet.

[jmcS4]

^^^ 40 valve engines, 5 per cylinder

some of the belt driven 4.2's were 32v

[GaretS4]

Oops - thanks for the correction. I really did know that. I must have been thinking of the SL.

[arrogntbastrd06]

Unless you know the complete background of your engines' maintenance history (including frequency and specifications of oil used) and the previous owner's driving style, I wouldn't rule out excessive engine wear with oil getting past the rings and valve guides. This engine has 32 valve guides which is a lot of potential entry points. Engine wear can be accelerated by both infrequent oil changes, using the incorrect weight for the season, or using the incorrect grade of oil, and increased engine loads. There are a series of tests that can be performed to determine wear location. That said, even when you do everything right and your engine is in prime condition, these engines will use oil when pushed hard. So lets consider the oil in your crankcase and ones' driving style to see how they impact oil consumption.

1. The oil factor. There are huge differences between the breakdown rates and volatility (evaporation) of the various engine oils. Oil can shear and split into smaller length molecule. High engine loads lead to greater sheer forces. Lighter weight oils (as used for winter conditions) have more smaller oil molecules which can move past tighter spaces such as rings, guides, and seals. Engine tolerances also change as the engine heats up. Some spaces close up whereas others may increase. Smaller molecules also tend to be more volatile and will move out through the crankcase vent or seals. Synthetic oils tend to a greater resistance to shear forces and have lower volatility, though not all are equal. A bit of internet searching of oil brands led me to Amsoil's site where they actually provide volatility, high temp /high shear viscosity, and wear ball test results. I haven't found similar test results from the other brands, but I'll keep looking. Note that these engines require AECA A3/B4 rated oil which are full SAPS and and designed for added wear protection. Anything else is a disaster in the making. Do you have a oil change/grade history of the car?

2. The driver factor. Higher engine revs and increased engine load from fast acceleration or higher road speeds leads to higher engine temps and pressures. This results in greater oil sheering force leading to smaller oil molecules, which combined with higher temps leads to a thinner oil, increased volatilization losses, and/or slippage past the rings and guides.

Using my car as an example, it's a low milage (40K miles), recently acquired 05 S4 with a maintenance history going back 6 years. Oil changes were frequent and well within the manufactures specs. Oil grade was correct except for one instance when they did not use an ACEA A3/B4 grade. The car came with a fresh oil change which was Castrol Edge European Formula with SPT 0W-30 (ACEA A3/B4). I live in northern Canada so the oils weight was acceptable for winter driving. Initially I drove the car gingerly and saw only minimal oil consumption; the equivalent of a quart in 2-3 thousand miles. As I got to know the car I began to push it harder using more of the engines upper rev range, accelerating quicker, and use the engine's compression for braking. I then noticed an increase in oil consumption at about a quart in 400-500 miles. I recently made a trip to the rocky mountains and did some spirited driving on isolated secondary roads having steeper grades and lots of switchbacks, meaning lots of gear changes and acceleration bursts. It was a great drive but in one afternoon the engine used 1 quart in about 200 miles. I was a bit shocked to say the least, but I shouldn't have been surprised what with pushing the engine hard and 0W-30 oil weight in the crankcase. This spring I changed to Castrol Edge EU Formula 0W-40 and after 3000 miles consisting of a road trip of 800 miles, several 200 mile trips plus around town driving the oil level has hardly moved on the dipstick. I haven't done any hard charging since the trip to the mountains so can't say what the impact of that sort of drive would be on consumption, but I'm sure there would be some. For comparison,I also have a 96 SL500 that has an aluminum cylinder block that I believe uses the same technology as Audi for hardening the cylinder wall. One thing I came across in the Mercedes owner's manual is the importance of checking the oil level after spirited driving and after high speed motoring as oil consumption will be increased. I find the SL's oil consumption to be minimal, though it is only a summer driver and gets Mobil One's European Formula 0W-40 (ACEA A3/B4 as specified by manufacturer). The SL's engine doesn't rev as high as the S4, has taller gearing, plus it has an automatic transmission, which is great for loafing around town or cruising on the highway, but doesn't inspire one to the same degree of spirited driving as the S4.

I hope you are able to identify the source of your engines' excessive oil consumption and it's nothing to serious.
Garet.

Great synopsis! What you see in your consumption pretty much mirrors mine (although i've got roughly 110,000 miles on my ODO).

With Liqui-Moly 5W-40 refreshed every 3-5k, and conservative driving she only consumes a quart of oil every 2000 miles. The minute I start driving like an a-hole, she'll consume as much as a quart in 250 miles. I have to imagine that general wear of the internals, the constantly failing gaskets (top and bottom of engine, as well as oil pan), failure prone check valves and pcv have something to contribute. As long as there is no scoring and no emissions codes I guess I just keep filling her up

[4point2]

With Liqui-Moly 5W-40 refreshed every 3-5k, and conservative driving she only consumes a quart of oil every 2000 miles. The minute I start driving like an a-hole, she'll consume as much as a quart in 250 miles. I have to imagine that general wear of the internals, the constantly failing gaskets (top and bottom of engine, as well as oil pan), failure prone check valves and pcv have something to contribute. As long as there is no scoring and no emissions codes I guess I just keep filling her up

Yeah that sounds about right. That's pretty much bang on where i'm at. I just keep on topping off and drive around with a 5Litre jug all the time, lol