I just wanted to share this--last week I was doing my yearly oil change on the XJ and also replacing the pan gasket since it was starting to seep. To my surprise, after draining the oil with the drain plug I found the pan retained over 1/2 a quart. The placement of the drain plug is such that it will never allow all the oil to drain out.

For 15 years I've wondered why the oil gets dirty 5 minutes after a change, here's why. Will look into a vacuum extractor for the next change.

I realize 1/2 qt in an 8 qt system will be negligible, but if I can easily get more of the used oil out of the pan I think it's worth it.

Also if anyone is contemplating a oil pan gasket it's a very easy job. Just follow the torque sequence in the service manual for reinstallation.

 

On my 2003xj8 4.2 with almost 370.000 km my oil stays clean for about 5000km. After oilchange the level on the stick is barely recognisable.
on my 2004 xj6 ( got it in may24)with only 145.000 after all those years I did it twice in 2500 with oil flush right after driving . Right before closing I poured another half a quart to rinse out the rest of residues