With the older air-cooled 911s such as the 993, the operation of the oil-level gauge is completely different than the ones in the newer water-cooled 911s like the 996 and 997. For the 993, the oil level is checked with the engine fully warmed up, running, and when the car is parked on level ground. In the discussion you mentioned, I recommended running the oil level approximately one quart low — or about half way between the two marks on the dipstick. I went on to recommend running the oil all the way down to the “add oil” line and then adding one quart. This advice does not apply to the newer cars, as they have a different oiling system with less total oil capacity. Do not use 993 oil-check methods in your 996!

Let’s look at your 996’s dash gauge and try to figure out what it’s telling us. Porsche says the distance between the maximum and the minimum marks on the digital oil gauge represents about 1.5 liters or 1.585 quarts of oil. There are six lines between those two marks, so each line represents about 0.246 quarts of oil. Porsche also says to add a half a liter of oil at a time. For our purposes, let’s call it a half a quart. Therefore, we can let the oil level drop two lines on the gauge before adding a half quart of oil. I would not bother to add oil in smaller quantities, as you will only confuse yourself — and probably the car, as well.

How you check your oil level will result in different readings. When you check the engine oil cold, you will get a higher reading than with the other methods. All of the oil has run back into the sump, resulting in this higher reading. With the various warm-check procedures, there is always going to be some oil off in the far corners of the engine, so you will get a resulting lower reading. We know that Porsche wants you to check the oil level when the car is parked on level ground and not running. And, as you say, there are four different ways to check it:

1. With the engine cold when you turn the ignition key to “Accessory.”
2. By switching a warm engine off then turning the key back on and waiting for the timer to run down to zero.
3. What Porsche calls the automatic oil level measurement when you are fueling. The motor must be warm. This presumes the engine is shut off for a few minutes (about five) but less than 15 minutes. When you turn the key back on, the measured oil level is displayed for approximately one minute.
4. The old fashioned way, with the dipstick (for all but 996 Turbos).

I prefer to check the oil when it’s cold in my cars because the reading is more consistent when the engine is cold than with the other various methods. If the level is less than one line down, I essentially ignore it as well as the other readings and check the engine oil level cold before I drive my Boxster again. Once the level drops to the first line below maximum, I pay more attention to the other readings. When the other checks indicate two lines below the maximum level, I add a half a quart of oil.

Incidentally, the procedure for the new 997 is a little different. That’s because the 997 and 997S no longer have dipsticks. So you will have to rely on the digital dashboard gauges to check your oil. Also, the difference between the minimum and maximum marks on the gauge is now approximately 1.2 liters or 1.268 quarts — so each segment on the display represents approximately 0.4 liters or 0.4227 quarts of oil.