Here is go again....I have a 2001 996TT (still under CPO warranty) eating 1qt ~450 mi and despite having all consumption documented through the dealer PCNA is giving me a hard time to fix the problem. They want me to do 3 more months of consumption tests (drive to the dealer every 500 miles to measure engine level) but apparently they believe that the car's oil gauge is not sensitive enough so before they pull a fast one on me, I want some ideas from people as to what is the BEST/MOST ACCURATE way to measure oil consumption. Below is what I have done so far:

1-waited for oil to drop to lowest level (1 bar left below arrow)
2-Dealer added 1 full qt (oil goes up 4 bars)
3-Return to dealer when level is at lowest level (1 bar left below arrow)

I guess a more accurate measurement may be to
1-add "13qts (correct full capacity? )
2- drive 500 miles
3-empty system and measure how much is left (of course some is stuck in the oil filter so dont know if this is perfect).

Other Ideas?

 

it's not as good for the motor to drain it, and you still aren't sure
you drained it down to the same level each time.
The best way is to repeatedly record your mileage, fill, drive,
top off, record amount added and rerecord mileage. After 5 or 6
top-offs, you will have averaged away any inaccuracy in the
measuring system.
Joe