First off I want to give thanks to the existence of this forum for without it I wouldn't even attempt some of these repairs. All of you share your knowledge and experiences to further the cause of these fine cars.
I purchased a 2003 XK8 on New Years Day 2018. A one owner, garaged kept, Florida car in very nice condition for its 88k miles. Had a couple of problems but none that couldn't be handled by a reasonably competent mechanic(me)! The transmission however had the dreaded 1/2 2/3 gear change wallop! When coming to a slow stop the downshift to 1st was a thump. Having no service records to examine, I decided to drop\change the pan to have a look see. There was no debris on the magnets and the bottom of the pan had no shavings of any kind. Wiping down the pan I found a date stamp for 2012 so a service had been done around that time. I took great care to contain the fluid so I could determine the volume. Bought one of those pressure pots for garden insecticides and modified the wand to deliver the Mercon SP fluid into the fill port. After dumping 4 quarts of fluid into the pot, I poured the old stuff into the quart containers and determined that I drained 3.5 quarts.
Installed the new pan and began the fill routine as instructed elsewhere on this forum. Injected a total of 5.5 quarts. Cleaned up and took it for a test drive. HOLY COW!! Wonderfully smooth shifts, no more thump when stopping, no more gear waver between 4/5 that wound happen on those rare cold mornings here in FL. This has transformed this car from a car I liked to a car I LOVE! Couldn't have done it without the help this forum has provided.

 

Be sure to do another Mercon SP drain-and-fill within the next couple thousand miles if not sooner. You want as much of the mix as possible in your ZF 6HP26 to be fresh ATF....

 

Planning on it. But first The wife's 2001 5 speed is next. I don't have all of the service records for it. I believe the process is the same but without a whole new pan. I want to make sure it has been serviced.