There has been much written on this and other sites about when and/or if one should change the "filled for life" fluid in their ZF6HP26 transmission. Moreover, what fluid to use and who should do the change. After much research and nashing of teeth I decided to pay the freight and have my Jag dealer do the job. At 40,000 miles the fluid was a very dark brown (near black) in color, having a slight burnt oder. There is no question that the fluid had lost a marked fraction of it's chemodynamic properties.

At a cost of $900 the Jag dealer replaced the pan (the filter is integral to the pan) and 6 liters of fluid. Aside from the peace of mind the Transmission shifts flawlessly and I could not be more pleased. Yes, $900 is a steep price to pay but it is far less then the consequences of a failed ZF6HP26. Debate it if you will but this is one job that needs done well before 100,000 miles and it's best done by a Jag Tech Pro.

Tim V.
2005 XKR Coupe
Florida