I just did my oil change for the first time on my new to me 2004 coupe. I did it on ramps, did a very long drain, probably over an hour, and the car took exactly 8 quarts to reach the top of the hatch marks.

I have driven it and checked the oil several times, that level is correct.

My only conclusion is to why I couldn't get that .5 qts out is that this particular car and oil pan would need to be level. Most vehicles I have done oil changes on actually drain better on ramps or nearly equal on ramps or flat. But you can see how the drain pan on this car would be better level.

That being said, .5 quarts isn't a big deal to me, especially when you consider total volume of oil is 8.5 qts.