Oil light coming on occasionally with hard use: A4 B6

(Oil level is correct)
I recently bought an A4 B6 1.8T Q with 36k miles. I have put on about 2500 more.
The oil light 1st came on after driving for about 5 hours with only 1 or 2
short stops. I was going about 80-85 mph when it came on. I pulled over and the level was about in the middle of the hashes. I topped it off with oil that was in the trunk from the previous owner (it wasn't synthetic) and started driving and it came on within a few minutes. I stopped again and waited a few minutes and then drove another 1.5 hrs at a slower speed with no problems.
I then changed the oil myself replacing the Audi filter with another one from the dealer and filled it with mobile1 5W30 (even though the service notice on the dash says it's not due for more than 200 days and over 6000 miles). No problems on the return trip and a couple of shorter trips, but then this weekend it came on again after driving about 5.5 hrs. This time I was in the mountains at 50 - 60 mph and it would come on for a few seconds at a time, only when the engine was straining to get up hills.
The engine doesn't seem to be burning any oil.
When I was buying the car I think the previous owner said he had had the oil pump replaced (I have a terrible memory). I don't know why that didn't raise any alarms in me, but he is a friend so I wasn't in skeptic mode.
I wish I had removed the oil cap and peeked inside the engine before buying it, because it is very sludgy in there. I scraped some of the gunk away with my fingernail and it still shows 1000 miles later. I'm thinking that is the problem and the oil pump was probably fine.
What kind of sensors turn on the oil light? Level and pressure?
Thanks --Art
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Well, I think you're into the sludge pproblem now - replacing an oil pump before 36,000 miles isn't the norm, and may indicate that it was already clogged up.... And you seem to have the classic signs of sludge. Do a Google search on '1.8t sludge' and read about it. Unfortunately, I didn't see a remedy (i.e., a way to remove the sludge). I would ask your friend for all of his receipts for oil changes; bet he was a little lax.... Or followed Audi's schedule, which was lax as well....
Dan D '04 A4 1.8Tq MT-6 Central NJ USA
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Sounds like a sludge problem. Search on audiworld.com for more info but here's a link to a letter from Audi on the problem http://forums.audiworld.com/a4/msgs/2137644.phtml
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"Art M" wrote

Sounds like the sludge issue - a result of Audi dealer using cheap mineral oil at 10K mile intervals. Take it to the dealer. The car must still be under warranty, and definitely under the extended "sludge warranty". Assuming the previous owner stuck to the required maintenance schedule (it was free, so I'm sure he did), then you should have no problem with AoA taking care of this. The best thing would be to get a new engine, but I don't thing AoA allows that. They just clean up the sludge, maybe replace the oil pump, and start using an oil that meets the VW 502.00 spec. BTW, the M1 5w-30 you used doesn't meet this spec, but hopefully AoA will not hold it against you - it's still a good oil. For the future, if you want to stick with M1, use their 0w-40 grade.
Good luck.
Cheers,
Pete
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Thanks to everyone for your advice. I took it to Audi yesterday. I'll take it back on Monday when they can look at it and I can drop it off. At first they tried to tell me that the previous owner was 1000 miles late on the first oil change and a few k on the next. I talked to them about the change in oil, filter and interval spec from the original manual. Near the end of the conversation the Assistant Service Mgr surprised me by bringing up the possibility of putting in a new engine depending on the condition of the engine. Are there any measurements or computer codes that would indicate the engine needs to be replaced? I'd like to know this so that I can fight for one if it is warranted.
Just out of curiosity, does anyone know why many syn 5w30 oils are in the spec, but the M1 is not? Is it that the 0w40 spec is better and other brands don't make 0w40?
--Art

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"Art M" wrote

Not to my knowledge. I guess if the dealer decides that the amount of work involved in cleaning up the engine is too much or if they would not be able to effectively remove all the sludge, then they may choose to put in another engine, most likely a rebuilt one. If the oil flow was severely restricted, then your turbo may be damaged as well due to lack of proper lubrication. Make sure they check that too and replace if needed.

Generally it has to do with how well an oil is formulated to withstand longer oil change intervals and still stay in grade. Some 5w-30 oils may have never been tested against that VW spec. Most oils meeting the ACEA A3 spec (european oil agency) also meet the VW 502.00 spec.
Honestly, even though M1 5w-30 doesn't meet the spec on paper, the used oil analyses of it I've seen after 10K miles in 1.8T engines look better than those of M1 0w-40. But, just to cover your butt and not give any reason for AoA to deny warranty, you should choose an oil that does meet that VW spec. As you've seen from the link provided by Ian S, there are plenty to choose from. And there are more, which aren't on that list, like Amsoil 5w-40 or Motul Ester E-tech 0w-40.
I'm running Castrol SLX 0w-30 in my 1.8T. It's known as Castrol Syntec in the US, but only if it says "Made in Germany" on the back label. If it says "Made in USA", then it's not the same oil.
Good luck!
Pete
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There's a recall on some 1.8T's because of a sludge problem.
Also the standard filter has been superseded with a larger unit.
Visit your Dealer ASAP.

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So their diagnosis:
"Oil lamp coming on. Performed oil pressure test. Veh had sufficient PSI. Ran veh & found oil level sensor inop intermit after veh gets hot. Replaced oil level sensor & changed oil. Oil was dirty & need replacing along with new filter." (Mileage: 39937)
Oil had been changed 1900 miles / 2 weeks before. A malfunctioning sensor seems inconsistent with what happened as described in the quoted text below. They didn't do anything to clean the engine.
They want me to come back in 2,000 miles for my 40K service and another oil change.
Sounds like the run around to me.
Records indicate the following related to oil (Audi dealer service except where noted):
11610 miles --- 10K service (oil change)18769 miles --- Audi service but no oil change
24081 miles --- 20K service (oil change, 12471 miles since last) OIL PUMP CHANGED Oil light had come on
(2004 Aug - AUDI Oil sludge letter)
34535 miles --- 30K service (oil change, 10454 miles since last) Oil light had come on
38081 miles --- I changed oil Oil light had come on
39940 miles --- Oil change. Replaced oil level sensor Oil light had come on
Any more advice?
Angry customer, --Art

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If this is the 1.8T engine the 'coking' issue can involve more than just the oil pump that the dealer replaced.
Probably should replace the oil lines to the turbo and be sure that the updated heat shield in installed.
Be sure to use the larger recommended updated oil filter from Audi.
Use the correct oil that was in the 'coking' advisory letter. Mobile One 0W40 and others are on the list. These oils can withstand the higher temperatures of the 1.8T without coking.
TonyJ 98.5 1.8TQM
Art M wrote:

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snip
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Art M wrote:

If what you see is a foamy tan looking goo you might have a problem with the head gasket leaking coolant into the oil. If so that it a big issue that needs to be corrected by pulling the head and replacing the gasket.
There are conditions where condensation from short drives combined with cooler ambient temperatures can cause this goo and the only thing it needs is to just drive a longer trip allowing the system to warm for a longer period of time to evaporate the moisture.
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I don't think so. It's black and tar-like, currently about a mm thick, but more gunk in the corners that I can see such as on the plastic oil deflector. When I changed the oil about 2000 miles ago I scraped some of it away with my fingernail to reveal shiny metal. That mark and the metal is still visible so not much new sludge, but plenty that was already there.
--Art
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Good grief! The oil is supposed to get dirty.
Is the oil light still coming on after replacing the sensor?
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Not yet, but I've driven it less than 100 miles since then, and both episodes happened after 5 hours of driving with only one or two brief stops.
Hell, I just looked in the manual and saw that the oil level indicator light has the word MIN printed with the oil can icon. The indicator light I had was for oil PRESSURE just as I thought and as the symptoms indicated. I'm thinking of installing one of those after-market dial pressure gauges so that I can get a better idea of how bad the problem is, but I don't want it to look jury-rigged.
Anyone have any advice on how to be a squeaky wheel and actually get some beneficial service done to it?
--Art
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stops.
light
it
I would recommend that you attempt to duplicate the conditions under which the oil light previously appeared and see if it comes back on. The problem is if you don't get the oil light to come back on, you won't have much of a case to argue. Your oil pressure switch is on the oil filter bracket and from what I can see in the manual, you remove the switch and then install the appropriate fitting with tubing to your oil pressure gauge. With engine warmed up, Bentley manual says you should get more than 14.5 psi at idle and more than 72.5 psi at 3000 RPM. Haynes says at least 29 psi at 2000 RPM. It is also possible that the recent oil changes have removed some of the gunk. If the light doesn't come back on and your oil pressure measures OK, then I would use one of the recommended synthetics http://tinyurl.com/82xga in a 5W-40 formulation (not xW30) and do several oil changes over the next 10,000 miles.
IMHO this would not be a car I'd be looking at keeping for the long term. Because Audi stupidly increased the oil change interval and allowed continued use of dino-oil, there was no longer any safety factor to protect the owner who went slightly over the maintenance interval. Because of that, your engine has been essentially abused in its early life and the resulting excessive wear on internal engine components has probably shortened their lives considerably.
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Audi dealer is pushing for frequent oil changes to gradually remove the sludge. You would think they would at least clean the valve cover and oil pan to eliminate a large portion of the sludge so that the filter wouldn't clog as quickly. Assuming it does clean up and then I have an engine failure within the 8yr warranty extension, do I still have a case? I think I'm going to send in that reimbursement card included in the letter for the oil change that I had to myself just so they have a record of my complaint about the sludge. Nowhere in the service records is the sludge problem mentioned. This even though the oil pump was replaced before 25k and there have been complaints about the oil light coming on at every service visit from that point onward.
Thanks for the advice.
--Art
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