Low Oil pressure at Idle

[isaacallen73]

Hey everyone, I've been lurking around these forums for a long time since i got my car, but this is my first time posting

Just as an intro, I have a 2006 A4 2.0T 6MT. At 124,800 miles now. Last oil change was at 120,500 (4,300 miles ago). Oil used was Castrol 5W40 Euro Blend.

So... A couple of days ago was the warmest day of the year around here (95 degrees f) and I was in some stop and go traffic on the highway due to a construction zone on an uphill. I had 3 people in the car, 3 heavy mountain bikes, and a whole bunch of gear, so the car was definitely loaded down. I saw the coolant temp creep up to 220 degrees (when the radiator fan kicks in) and right as the radiator fans kicked in the low oil pressure light came on. Being in a construction zone (1 lane and no shoulder), I wasn't able to pull over. Soon after this, traffic started moving and once i got up to 20 mph the light went off. I pulled over at the end of the construction zone, let the car cool off for a few min, and checked the dipstick. The level was right in the middle of min and max. Regrettably, I kept driving, but i was extra careful to be easy on her. Ended up driving about 50 more miles that day. Fuel consumption didn't change a bit, no noises.

When I got home, I started researching low oil pressure in these engines and realized that it is more serious than i thought. None of my local auto parts stores had an oil pressure gauge so i had to order one off amazon. After riding my bike to work for two days, i finally got the gauge in the mail today. Here are my readings:

Immediately after start: 62 psi
cold idle (coolant temp 118) 30 psi
cold 3k rpm 67 psi

warm idle (coolant temp 200) 11 psi
warm 2k rpm 45 psi
warm 3k rpm 63 psi

When revving, the gauge bounced around quite a bit, so those numbers are averages.

So, my question is what should I do from here? It seems like my pressures are within spec while revving but are a bit low at warm idle... From what i have read, that tends to be wear on bearings in the engine (cringes). For only having 125k miles, it seems a bit early for that.
Also, from what i have read, sludging is a common problem, but that affects pressure at high rpm which doesn't seem to be my case.

It is also worth noting that i just came back from vacation where i did some big highway climbs and was really pushing the car on a hot day. Is there any chance i cooked the oil doing that? Didn't turn off the car right after pushing it or anything, but was wot for a good amount of time. Would it be worth just changing the oil and filter? Im 700 miles away from my next oil change.

Thanks for reading this mega long post. I appreciate any help.
Isaac

[rongeur]

First of all, thank you for approaching your problem and question to this forum intelligently. You did some great baseline diagnostic testing and did your homework on your oil light issue. A couple of things I would check / do in addition:

Scan for any codes. Marginally low oil pressure can throw some non-CEL codes relating to engine functions that use oil pressure to work. For example, a P000a code may populate due to a slow to respond N205 / camshaft adjuster mechanism. It is my understanding that this function is affected first.

I would recommend changing your oil early and consider adding a flush product prior to draining your oil. I have used Motul Engine Clean in the past without problem. If you have some easy to clean residue, this may help clear passages, but I suspect at 5k intervals with a good synthetic, sludge is not an issue.

Also, our cars do get some fuel dilution into the oil which can thin the viscosity out some and this will lower pressure at warm temps. Heavy load (up hill, heavy weight load as well) for prolonged period will require more fuel than cruising and you could have diluted your oil more than normal driving would have. Changing oil would fix this as well.

Finally, consider sending out you old oil for an oil analysis from Blackstone. It is 28 bucks and they can give some insight on the condition of the engine wear and oil condition. Free sample kit at your request to their website. Just follow their instructions online.

This what I can think of without freaking out about internals. The good news is you have no concerning sounds or ticks.

[isaacallen73]

First of all, thank you for approaching your problem and question to this forum intelligently. You did some great baseline diagnostic testing and did your homework on your oil light issue. A couple of things I would check / do in addition:

Scan for any codes. Marginally low oil pressure can throw some non-CEL codes relating to engine functions that use oil pressure to work. For example, a P000a code may populate due to a slow to respond N205 / camshaft adjuster mechanism. It is my understanding that this function is affected first.

I would recommend changing your oil early and consider adding a flush product prior to draining your oil. I have used Motul Engine Clean in the past without problem. If you have some easy to clean residue, this may help clear passages, but I suspect at 5k intervals with a good synthetic, sludge is not an issue.

Also, our cars do get some fuel dilution into the oil which can thin the viscosity out some and this will lower pressure at warm temps. Heavy load (up hill, heavy weight load as well) for prolonged period will require more fuel than cruising and you could have diluted your oil more than normal driving would have. Changing oil would fix this as well.

Finally, consider sending out you old oil for an oil analysis from Blackstone. It is 28 bucks and they can give some insight on the condition of the engine wear and oil condition. Free sample kit at your request to their website. Just follow their instructions online.

This what I can think of without freaking out about internals. The good news is you have no concerning sounds or ticks.

Thanks a bunch for the reply.

No codes as far as i can tell. My Ultragauge gives me trouble codes and pending codes and there are none. I assume codes like the ones you described would show up there?

I will certainly change the oil as soon as I can. In my hours of research, I never came across fuel dilution as being a cause for low oil pressure. Makes total sense, especially because our cars run on the rich side. I'll probably take a sample when I do the change and then retest the pressure. Depending on that reading I'll decide if I want to send it out or not.

Out of curiosity, what oil do you use?
The guy I bought the car from was an Audi mechanic and he exclusively uses Castrol 5w-40, but it is quite hard to come by (Castrol 0w-40 is much easier to get, as well as 5w-40 from other companies).

Thanks,
Isaac

[yeoj112689]

I hate to bring this to you but I had the same problem and ended up doing a 1.8t oil pump swap. The problem from what I have read is that there are 2 balance shafts in the oil pump and they tend to cause issues and you end up having low oil pressure or throwing bearings.

I threw the code and instantly pulled the car over, pulled the engine, did the swap, and have had zero issues since.

I honestly couldn't tell you if my pump was/is bad but I was not willing to risk it. The problem is a new 2.0t pump is 1-1.5k and a giant pain in the ass lol.

I still have my old pump if you want it you can have it to try and make something work (people have done shaft deletes) if you pay the shipping(and maybe a 6 pack if you're feeling generous :D) its free with everything including the gears and chain.

Keep us updated as I went through a whole process with this. Its not going to be fun but doable. I wouldn't drive it though as there are good chances you will throw a bearing and thats pretty much leading to a total rebuild.

I say go 1.8t pump but its about 300-500 to do that so its up to you. PM me if you want I can give you my number for any instant questions because I know how frustrating it can be.

[rongeur]

I use Motul 5w40 Xcess at 5k intervals and have never had an issue with it. Castol is what the dealership use, or at least used back when mine was still serviced by them back when I first purchased CPO.

This is a great thread if you havent found it yet.
http://www.audizine.com/forum/showth...leshooting-DIY

[isaacallen73]

I know this is an old thread but I figured I should update it if anyone else has a similar problem.

I ended up just doing an oil change and the light hasn't come on since (about 4,000 miles later). Problem solved!

Isaac

[pimpbot]

I know this is an old thread but I figured I should update it if anyone else has a similar problem.

I ended up just doing an oil change and the light hasn't come on since (about 4,000 miles later). Problem solved!

Isaac

Have you rechecked the oil pressure since the oil change? Seems like 11 psi at warm idle is low, right?

Right now, I'm fighting rough idle and some valve noise at idle. Once the engine gets really hot, it's smooth at idle, but still some valve noise. Most of the time, there is noticeable vibration at idle, but it's worse when it's cold. I'm about to dig into checking my oil pressure, so maybe that's it. The car does have 200k miles on it, head replaced at the dealership before I got the car at around 70k miles. I wonder how much of this rough idle is due to carbon buildup, but that's another project.

[Jeevan]

Have you rechecked the oil pressure since the oil change? Seems like 11 psi at warm idle is low, right?

Right now, I'm fighting rough idle and some valve noise at idle. Once the engine gets really hot, it's smooth at idle, but still some valve noise. Most of the time, there is noticeable vibration at idle, but it's worse when it's cold. I'm about to dig into checking my oil pressure, so maybe that's it. The car does have 200k miles on it, head replaced at the dealership before I got the car at around 70k miles. I wonder how much of this rough idle is due to carbon buildup, but that's another project.

11 PSI in a bit low. Also vibrations are normal on the old engine with 200k, I would check engine mounts, oil pump play, carbon buildup and valve train wear and tear.


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[Jayz691]

Yeah, carbon buildup will def affect idle and response. 11psi is low, but not horrible. Also depending on where you put the sending unit. I have mine on a banjo port, at the turbo, and at warm(hot) idle its between 12-15psi. But ive heard it can read a few psi under in that location, so idk.

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[EvolutionArmory]

I wonder what brand oil filter he had in there and how it looked when he took it out?

A crushed one would probably have affected his pressure at RPM too but who knows.

[Theiceman]

Have you rechecked the oil pressure since the oil change? Seems like 11 psi at warm idle is low, right?

Right now, I'm fighting rough idle and some valve noise at idle. Once the engine gets really hot, it's smooth at idle, but still some valve noise. Most of the time, there is noticeable vibration at idle, but it's worse when it's cold. I'm about to dig into checking my oil pressure, so maybe that's it. The car does have 200k miles on it, head replaced at the dealership before I got the car at around 70k miles. I wonder how much of this rough idle is due to carbon buildup, but that's another project.

im not sure he will respond since his last post was over 2 and a half years ago .

rough cold idle , id be looking at my PCV i think first, its a maintenance item and pretty cheap.