Oil pressure light

[cfree5119]

Yesterday I took about a 9 hour trip in my 03 Audi A6 Quattro 3.0l. About 3.5 hours in the oil pressure light goes off. I pull over, don't hear in knocking, the oil level is fine, etc. I turned the car off for a minute, started it and when I put the car into "R" the light said okay. Once back on the road it did it about 15 miles later. At this point I stopped to get gas and did the same procedure as what I did earlier. On the interstate I maintained a speed of 75 - 80 mph.
Now I switched to smaller a road and cruised between 65 -75 mph. I did not see the light come on for another 140 miles or so. It went off, I pulled over, turned the car off for a minute and then headed on my way. Did it 15 miles later and then went another 80 miles before I got to my destination where it did it when I got off my exit.

I am running Castrol Syntec 5w30 that was put in the car 500 miles ago (first time its seen highway since switching to Castrol from Mobil 1) and the weather was between 27 - 35 degrees the entire day.

Any thoughts? Bad light? Can't be the oil pump can it?

 

[Gary Allan]

I'd figure the sender/sensor, but I'd also change the filter to see if that eliminated the problem. The Teutonic's like high bypass valve ratings. The filters are usually more on the sieve side, but I'm sure that they too can load up.

 

[lipadj46]

If it was the oil pump I am guessing you would be shopping for a new engine after that trip. I would still put an oil pressure gauge on it and measure the pressure at idle and various RPMs.

 

[JHZR2]

syntec 5w30 is not the right oil for that car more than likely. Does it carry the right VW and ACEA ratings?

 

[38sho]

Originally Posted By: JHZR2
syntec 5w30 is not the right oil for that car more than likely. Does it carry the right VW and ACEA ratings?


come on man, there are so many vw/audi cars on the road out there not running the right oil.... atleast the guy runs a synthetic........

x2 on hooking up a gauge to the engine.... this is a nice defintive test to check what the engine is really putting out

 

[Silber Igel]

Originally Posted By: JHZR2
syntec 5w30 is not the right oil for that car more than likely. Does it carry the right VW and ACEA ratings?



When you hear hoofbeats in Arizona, you don't look for Zebras...

I'd be double sure you are using the VW-Audi recommended GRADE oil for the car. VWs are picky ... the Mobil 1 site suggests 0W40 Probably the best choice... or 5W40.

 

[JohnBrowning]

Check the wire for the sender. I had problems with older TOyota's when they would get about 12 years old or so the rubber/plastic boot that helped hold the single wire to the oil sender would gethard and not hold tight. The conector was just a piece of brass that cliped on the end of the sender. THe sender side looked like it had a Brass tack on the end that the wire and clip slid over. It would start to lose contact and set off the oil light. I would tightenthe brass clip up a bit and use a zippo lighter to gently tighten up the plastic/ruber boot and it would fix the problem.

If you had a real oil pressure issue it would show up with noise, lackof performance, excessive heat and foul smell as the oil burned.

 

[JohnBrowning]

Check the wire for the sender. I had problems with older TOyota's when they would get about 12 years old or so the rubber/plastic boot that helped hold the single wire to the oil sender would gethard and not hold tight. The conector was just a piece of brass that cliped on the end of the sender. THe sender side looked like it had a Brass tack on the end that the wire and clip slid over. It would start to lose contact and set off the oil light. I would tightenthe brass clip up a bit and use a zippo lighter to gently tighten up the plastic/ruber boot and it would fix the problem.

If you had a real oil pressure issue it would show up with noise, lackof performance, excessive heat and foul smell as the oil burned.

 

[Petrou]

ya its either the sensor wiring or the sensor. it could be an internal problem, but not that likely as you drove that distance and didnt have a problem. In ten years of mechanicing i have seen one oil pump fail, on a Caterpillar C-15, the trucker never checked his oil level and the pump burned up with the rest of the motor. Never seen an automotive pump fail. could be a pressure regulator in the motor could be a bad oil filter. but probably just some wiring or a sensor gone bad.

 

[lipadj46]

Originally Posted By: Petrou
Never seen an automotive pump fail. could be a pressure regulator in the motor could be a bad oil filter. but probably just some wiring or a sensor gone bad.


Guess you have never come across a 2003 Land Rover Discovery

They farmed out the engine production that year and the contractor's casting was bad and the dowels for the front engine cover were off a bit. This put stress on the pump and guaranteed failure of the pump. There is a TSB, only way to fix is with a new engine, no recall though. Just some some random semi OT trivia from an insomniac...

 

[mechtech2]

The light goes "off"?
That's a GOOD thing.

 

[hominid7]

If the oil presure sensor checks out (wire ok and not visually appear to be leaking) then i would agree with some of the others that your oil is not right. Germans like thick oil. My old Jetta would trip the pressure sensor with anything thinner than 15w40, and even that was not thick enough for Texas summers.

Syntec 5w30 is a bit on the thin side when compared to the Mobil 1 you were using previously. If you don't want or don't have access to VW/Audi approved oils, you can try a thicker traditional conventional or synthetic oil (xxW40), just don't use it for extended drain intervals.

 

[Rickey]

Thin oil strikes again !!!

 

[Silber Igel]

+1

 

[Gunatics_Adler]

I have seen one oil pump fail in my 13 year of working at the family shop. The gears blew apart in a cheap aftermarket 454 pump. I doubt that is the case here.

Id swap out the oil making sure you have the right grade, and putting a good flowing filter on it. If that does not fix it, then its the sensor or a faulty wiring issue.

I have seen the wrong oil and filter combo trip the light on a few cold starts, but never while going down the road. But then I tend to put thicker oil in a car, not thinner oil.

 

[cfree5119]

Thanks for all the input guys... could the car be subject to sludge problems?

I will probably switch from the Castrol Syntec 5w30 (not approved) to the Mobil 1 0w-40 (502 approved) and see what happens. How much does a oil pressure gauge cost?

Also, I have been driving for the past 2 weeks around town (no highway miles) and have yet to see the oil pressure light come on again.

 

[38sho]

just take it to a shop and have them check the oil pressure and sensor......

from what I understand, its a common problem on some Jetta's, my bro in law just had this problem on a 1.8T.......

if the oil is full, I wouldn't waiste it and drain it... I suspect something else is at issue here besides the oil.....

if you truly had a bad oil pressure problem, where a change in oil could effect the light to come on at idle.... you would more then likely have had some bad noises going on by now, and also the oil light would go out anytime you got off idle.... usually motors don't last too long when this is the case........


like I said, its ludacris how many people on here think a VW engine is going to blow up in 5 minutes without the approved fluid in it.......... If it were me, I'd be running an approved oil, or atleast something good... which you seem to have covered... [censored] near any synthetic in a 30 grade with the proper OCI will get that car down the road without massive destruction!

don't waiste your money like a fool!

 

[UNC017]

If the thinner grade oil were the core problem, you'd see the oil light at IDLE first, not at highway speed.

I suspect a bad oil pressure sending unit. But use the correct grade also.

RE failed oil pumps: I've seen one outright failure ('68 Ford 302 sucked a piece of plastic timing gear through the screen and seized, shearing off the intermediate shaft). I've seen others wear to the point that they couldn't maintain minimum pressure at idle- side clearances on gerotor pumps are very critical. AMC v8s were a bit notorious for that, IIRC.

Other extreme- just about every vehicle I've owned that had an electric pressure gauge has had a sender go bad eventually.