Oil level sensor truth??
 

09 911 4S oil change. Hot drain , also let it drain over night on level ground. 3.8 engine. Measured exactly 7 quarts 29 oz. (7.9 qts.) Installed new filter. Test drove to proper engine and oil temp. On level ground ,engine idling check onboard computer for oil capacity. Oil level at bottom line but not flashing.
OK ,I don't want to over fill. If I was to get the measurement to the top full line, I'd have to add more than a additional quart of oil. I have read different forums with similar issues, but no one has a correct answer. I have read where Porsche issued a statement that Oil level sensors were not the problem. SO is the true answer that oil sensor can be recalibrated? Can a Porsche Mechanic help answer this.

I have a 997.1 and find it to be more of a law of averages type of thing. Try measuring it cold on flat ground and see what your get. Then if it's still reading low, add 1/2 a qrt and measure again.

Thank for the reply. Will give see what happens

The word I get for the newer (DFI) engines is they have a 1 hour drain time or an overnight drain time. The two different drain times require different amounts of oil to bring the level up to where it should be.

I do not have those amounts. They may not be what is in the owner's manual. My tech sources tell me the oil quantity is tied to the car's VIN as mid-production run changes can affect the amount of oil the engine requires.

Briefly, the engine is brought up to temperature. The oil is drained for the correct amount of time. A *known* quantity of oil is added to the engine. The amount to add is provided by Porsche. The amount added by the tech is known by the tech referring to the read out on the oil despensing gun in the service bay.

Then the engine is run until the fresh oil is up to temperature and the oil level checked with the electronic oil level system. This should deliver the expected reading, which in the case of my 996 Turbo is with the read out at the max line not above or below it.

It is by following the proper procedure the tech not only drains the engine properly but adds in the correct amount of oil and thus can confirm the electronic oil level system is working properly.

So in your case I do not know if the 7.9 quarts was what you removed from the engine or what you added. In either case I also have no way of knowing it was the right amount. That the electronic oil level system may have been reporting the oil level at an acceptable level doesn't necessarily mean that all is well. There is the possibility (slim I admit) that the system is not working properly.

It could be for an overnight drain you need to put in more oil than would be required for just a one hour drain. In fact I have been told by the techs this is the case but I do not know the amount differences.

Where does this leave you? If you are sure you put in 7.9 quarts and you are sure of your oil level measurement procedure, that is you get the same level over and over again (one oil level sensor failure mode has the reading different when checked at different times but following the same and correct procedure every time) then add in some amount of oil -- ideally the amount that should raise the level one bar -- and see if the level goes up by one bar.

This at least tells you the system is working at some level (no pun intended). What you want to avoid is the possibility the system is not recognizing the oil level properly and you add a quart and the level doesn't change or changes by something less than the correct/expected amount so you add more oil and then at some point you have overfilled the engine.

Thanks for the great info. Going to add a min. amount of oil and recheck sensor operation.

Never heard of this......I am assuming my oil change is without old oil present.

An hour drain (with the engine hot) removes quite a bit of oil. An overnight drain (again with the engine at least hot to begin with) removes even more oil. How much more oil I don't know.

But there is always some old oil present in the engine even after an overnight drain.

On the 997.2 each segment =.4 litres, 3 segments =1.2 litres when at the minimum mark. iirc
The pain is that engine oil has to be up to temp before you can get a reading so you have to run your engine for quite a while after an oil change if you let it drain for an hour to find out where you are.

For the OP .... what was your oil level before the oil drain?...... I've got a 997.2 and have yet to have any issues with oil changes , I do know that if on non level ground I can easily get a 1 bar less reading on my indicator

For a 997.1/M97 and assuming a normal oil load and a warmed-up engine at the start, does anyone know the drain volumes at 15 minutes, 60 minutes, and 24 hours (either an absolute value or expressed as a percentage of starting volume)?

Being the originator to this post I thank you all for your input. What I decided to do is order a new Porsche oil level sensor. Will heat up the next decent day , might Snow, and drain the oil over night. Install new sensor and what ever oil it takes to get to the top max line. Will document the amount of oil for future changes and let er rip.