clcycle

my car is flashing the annoying oil light in the middle of the dash, its done this occassionally in the past but i knew for sure it has good pressure from checking it with a mechanical gauge. This past weekend i did a crank seal, a gasket for the oil pump cover/front cover, fixed a crack in the cover and reassembled. I filled the car with extra mobilone 5w20 full synthetic we had lying around the shop, and started it. drove it for 60 miles, oil light non stop was beeping, and flashing. Today i hooked it up to a mechanical guage. 35psi at idle, 60psi at 3000rpm. Checked the oil pressure sensor and found out that someone at some point installed a 1.8bar sensor and the car is supposed to have a 1.4bar, so i replaced it with a 1.4 and drove the car home from work. 20 miles and then... beeppp, the light starts again and is present non stop. When i did the front cover, i did an oil pan gasket as well, i cleaned the oil pump screen well, and kept everything clean enough to eat off of. So ive got good pressure, what could've changed to make this light go ape**** non stop? Could the 5w20 full synthetic have anything to do with it?

jcman

5w20 is too light for these cars and not what the factory suggests, stay with the recommended weights.

Just Me

Well, 0w20 is too thin - in my opinion vastly too thin, but i really don't think so unless its very hot where you are. Spec is 5w40 meeting ACEA A3/B4. Typically the culprits are the sender unit (which you have apparently replaced). I thought on these cars there were TWO senders and they had to agree - maybe that was just older 80s and 90s....

I don't know the spec for oil pressure, so i cant validate your mechanical readings. But it certainly does not sound dangerous. 1.4 bar is 20 psi, whcih is much lower than you measured. But did you measure with the oil HOT? 100 degC cst is typically about 1/5 to 1/8th the cst of oil at 40 degC. Note this is why we have and need multi-vis oil.

Grant

jcman

Start engine and increase engine speed (RPM) slowly, should see 1.2-1.6 bar (17-23 psi)
At 2000 RPM and an oil temperature of at least 80 degree C (176 degree F) oil pressure should be at least 2.0 bar (29 psi)

Are you checking the pressure at the sender port? , just asking.

clcycle

Prior to doing all this work, i ran conventional 5w30 for the past 5000 miles, since ive owned the car. So if im understand right, 5w40 is the spec? i dont have a manual so any definitive specs would be nice. I know there is an oil temp sensor on the front cover/oil pump cover, but i thought it was only related to the oil temperature gauge on the dash, not the blinking light, but i could be wrong. Tomorrow ill drain the oil in it, and swap it out for the correct kind if someone is able to give me a definite answer on what to run. This car is well designed, i dont argue that, but here in West Virginia, no one really knows squat about them or any of the specifics that there is about them. Even the closest dealer doesnt know hardly anything other than to have you trade in for a new one. Any good information is appreciated.

clcycle

Yes checked pressure with a MAC oil/trans pressure gauge, off the same hole the pressure sensor is located. Drivers side, back of the engine, just about the oil pan, behind the filter.

jcman

5w30 or 5w40 is fine, I use Shell Rotella t6 5w40 full syn in two of my Audi's and newer low mile 42K work van 08 chevy 4.3 as I did in 02 Astro 4.3 with 260K, many flavors and many choices I guess.

You do know about the oil temp/level sensor in the pan and the dash warnings from this sensor?

What dash warning are you getting is it red or orange?

clcycle

My oil light flashing on the dash is red. My audi has the provision for an oil level sensor in the bottom of the pan, but there is no sensor there just a cap that is mounted in its place.

jcman

That is the right port, OK.

jcman

If your pressures are good so far by the readings you see then it is possible that the wiring or connector is not good at certain times "rub or short", or the sender it self is bad.