Yeah, this has always puzzled me. I have been following the guidance similar to that above whereby I measure oil in my garage before driving (e.g., 24 hours+ rest time), but this is not consistent with the owner's manual.

 

Now I'm curious. Owning a 997.2 I haven't read the .1 manual. The next time I have a friend's .1 in for service, I'll pull out their manual. Sorry in advance if I've been wrong about this.

Edit: Thermal expansion on our cars can be significant!!!

I've always gone by what Petza says. So I'm only an echo chamber. Pete, do you want to chime in with your wisdom here.

Meanwhile, any chance of getting a shared photo of that section in the manual?

FWIW, the 997.2 was a big redesign. That includes the AOS, which seems to be mostly bulletproof. Still, with a car that doesn't burn oil, I run my 2010 at the bottom bar just to minimize possible frothing and resultant AOS strain. But friends who have oil burning cars tend to start high so they can end a drive low rather than too low.

One other thing ... From Porsche Technical Releases I thought the 997.2 measured oil level at the internal sump chamber. Thus the need to wait while the motor idled for the scavenger pumps to fill that chamber. If I'm not wrong about this, then the tilt of the car would matter a bit but shouldn't be as critical as if the oil was spread across the entire oil pan. As a counter argument, the tilt could affect his much oil was avaliable for the scavenger pumps to move to the chamber. That could affect the reading in either direction ... think about the tilt gyrations Bruce goes through when draining his oil!!!

 

I really wish the 997.2 had a physical dipstick. Prior to owning mine, every other car I would check before starting my commute or trip. Now I usually will let the car sit in the garage when I get home for about 15 minutes, then start it up and take a reading.

 

997.1 cold engine, last driven a day ago. ignition on.

How much oil should be added? I'm thinking a 1/4 of a quart. What do the wise ones say?

 

The Common Wisdom, to my knowledge, is that you don't need to add any. .1 cars are allegedly best left at one segment below full (like yours) or two segments below full.

And here's the Oil Measurement section from the .1 Owner's Manual...

 

It may be the opposite. The .2 cars are in the era of "hands off by the consumer". I believe they expect the end user to leave everything to the dealership and only put the measurement procedure in for nostalgia sake. The sensitivity and wonkyness would probably not accure on a lift anyway.

I was told the vehicle will alert the driver if anything is out of bounds, basically shut up and drive.

 

The 997.1 oil check is done when car is cold and sitting. If you attempt to check the oil with car warm, the oil monitor will not give you a reading until the car has cooled down.
Example: my experience if car has been running and you stop for gas, the oil monitor system will show a reading on the dash to wait 59 minutes befoire it will give you the oil reading.

 

Jake Raby has also said that one should only measure their oil in a 997.1 when the car has sat for 24h or so but I would say overnight is fine for daily driving.

In the .1, I have noticed that the difference between the bottom of the gauge and the top is LESS than a 1/4 quart. My car burns 0 oil in normal conditions. If you overfill it a bit, the car will self regulate somewhat to either burn off that excess oil or it goes somewhere. Otherwise, if the oil level is set properly, the gauge will not move even during 1k mile trips, or a week of roughly 50 mile commutes. Last, if the car sits for over a month at a time, I have noticed a bit of burn off but I assume that is condensation or something. After a drive or two, the gauge stays rock solid on my car (2006 C2S).

 

That is perfect, do not add any oil and allow space for the oil to expand.

And yes, you are correct it is a quart of a quart. But I wouldn't add, I keep mine like that all the time.

Best