the_silver_meep

Hi all,

Back again here with a question about oil level readings. Previously, after waiting for the countdown my oil level sensor on the dash would bounce around anywhere between the min and max bars on my dash oil level reading. The last times I've been checking it (on the dash) the value has been below the minimum bar, blinking as if it is low (see attached picture though not my car for reference). There are no blinking red lights, it is only the bottom black bar that blinks on the oil level sensor on the dash.

To confirm oil levels, I checked the dipstick by parking the car on a level surface, removing the stick, wiping it with a coffee filter, re-inserting it all the way and removing it again; 1) while the car was completely cold in the AM, 2) after I had driven the car 10 miles, shut it off and let it sit for 10-15 minutes following the owner's manual. I repeated these checks several times to confirm, every time I remove the dipstick the oil level is consistently right in the middle between the 'max' dot and 'min' dot (see attached image for reference on dipstick level).

My questions are; 1) am I doing something wrong in reading the dash oil level sensor? 2) from what I have read online, it seems like this dash oil level sensor is fairly accurate; is it possible I am not reading the dipstick correctly? 3) is it common for the oil level sensor to fail / produce inaccurate low-readings? 4) what next steps do you recommend?

A bit of background; I am extremely paranoid about this car. Having gone through the cylinder scoring / cracked head rebuild I nit-pick everything; due to this low-oil reading I have completely stopped driving the car and it has been sitting parked for a couple days now.

Any help is greatly appreciated. Thank you!

Note: this is not my vehicle! Just using this as a reference image.

Joel987

You could have a failing oil pressure switch or corrosion on the connectors. I would trust the dipstick over any electronic gauge. What year is your car? I noticed you don't have an analog looking oil pressure gauge.

The oil pressure switch is on the upper right side of the engine. You may have to remove the air box cover to reach it. Try disconnecting and reconnecting the wires. If the gauge starts working and stops after a while you probably have a soon-to-fail oil pressure switch.

DBJoe996

What weight and type of oil are you using? What is your oil pressure at idle? The oil LEVEL sensor is not easy to replace. In fact I think it requires the engine to be lowered. The oil PRESSURE switch is somewhat easily accessed for replacement, but it has nothing to do with oil LEVEL. I would suggest adding some oil to bring it up some on the dipstick and see how the oil LEVEL sensor reacts. One bar below maximum is acceptable.

the_silver_meep

It is currently Mobil 1 0w-40 synthetic; last oil change was about 2000 miles ago when I finished using non-synthetic 10w-40 for the engine rebuild break-in. Oil pressure at idle (after driving for about 15-20 minutes) is normal (I assume) at right around 1 bar. Jason with 9xx Motors in California suggested the exact same thing you do about adding oil to see how the sensor reacts, I will try this either tonight or tomorrow just haven't had time to do it yet unfortunately & I wanted to see if you guys thought I was doing something wrong / how common it is for these sensors to fail (from what I gathered it seems fairly uncommon?).

Thanks for the help.

Optionman1

It’s my understanding that using the pre-start countdown should be done only on a flat surface when cold, and the dipstick only when fully warm but after a 10-15 minute shutdown to allow oil to drain back onto the sump.

Mike Murphy

I would only check oil, stone cold in the morning and use that as a benchmark. And yes, rely on the dipstick more than anything else. If your sender level sensor is going, I’m not sure I’d worry about it.

My oil level changes depending on temp, how long I’ve been driving, etc. So I don’t care what it shows, other than what I get in the morning.

Joel987

I'm with Mike. I took readings on the dipstick when warm (after letting oil drain back into the pan) and then took readings when cold. I use the cold readings as my benchmark, knowing the reading will be higher when warm. Only German engineers would design a system to make you use your engine before checking the oil to check your oil.

I was thinking oil pressure switch because when mine went I'd get solid 5 bar cold and a little warm and then the gauge would drop to zero and the computer would flash low oil warning. My 02 (which is a late 01 build) has a regular oil pressure gauge (in addition to the computer). I didn't know Porsche changed to an all digital gauge in the 996.2.

Mike Murphy

Interesting. I didn’t know the two (pressure and level) were combined

plpete84

Wait what?? What does the oil pressure have to do with anything with oil level, which is what the OP is asking about. To clarify, the oil level sensor has a dual function: Oil level and oil temperature. Not oil pressure. It's located on the top of the engine near the oil cooler as indicated by the blue arrow in below image. If you remove the intake manifold from that side it's not a super hard job. No need to drop the engine. After doing the UAOS I can have the entire intake manifold (both sides) out in about hour and half.



Oil pressure sensor (below image) lives on the top of the passenger side head and is known to fail but should not affect the oil level reading at all. Your oil pressure arrow will act erratically or fail completely if the sensor fails or is failing.



@dashton654 - the best practice to check the oil on a level surface in the morning. This should give you an accurate reading. FWIW I subscribe to this, however, I noticed that after driving and putting the engine through a complete heat cycle I'd park the car on a level surface and go about some business, let's say grabbing some groceries. When I return to the car an hour or so later and turn the ignition on the reading displayed is the same that I've seen in the morning on a cold engine. Go figure. When in doubt, go to a level surface and trust the dip stick.

SoCal911t

https://rennlist.com/forums/996-foru...l#post17532557

the_silver_meep

Thank you, I'll be sure to do this tomorrow Morning. Another question I have is ideally, where should the oil sensor level be on the dash relative to where it is on the dipstick? My assumption is that if oil is half way between the min / max dots on the dipstick that it be halfway between the min / max lines on the oil level sensor inside, is this how it should be? I just want to confirm that my dipstick reading means I shouldn't be getting the low reading on the oil level sensor on the dash.

plpete84

Electronics fail so I'd rely on the dip stick first for this exercise while you figure out if the oil level sensor is bad. I don't know if a failed one would throw a code given that it also monitors oil temp. That would be good to know. It could be a soft code (not illuminating CEL) so scanning the computer with a Durametric would be a good idea. They levels should be very similar on both. In my case when I looked at this, my dip stick was always slightly lower than what the gauge displayed but by a small margin. Regardless, the best practice is to keep the oil level at 1/2 full on the dip stick or gauge. If you feel you need to add, add 1/4 of a bottle at a time. You DO NOT want to overfill so for this exercise I'd relay on the dip stick. No need to be hypersensitive about this either. If you're at half full on the dip stick but the electronic gauge is one bar below half full, I'd leave it be and drive. Last thing you want is to toast your AOS and start smoking upon start up.

Tarek9xx

off topic, but since you posted such a perfect picture of a pristinely cleaned engine, could you tell me what is the purple pointing to? I dropped my engine and it's sooo filthy down there. So jealous!
Thanks

Tarek9xx

Sorry I meant to quote this message in my prior post. Could you please tell me what is the purple arrow pointing to, in the first pic? Thanks and wow! what a clean engine!!

De Jeeper

Knock sensor

#33

http://www.autoatlanta.com/porsche-p...-05§ion=101-05