Being a new(ish) XK8 owner, what type of gearbox is in my late 2002 XK8 4.2?
A couple, say four times since my two months ownership it has been slow to change down to first gear when approaching a junction and goes in with a clunk. Could this be serious? I have been told that an oil and filter change may cure this. The car has only done 43k. (Documented) What sort of money would you expect to pay to do an oil and filter change with an Indie? And still waiting to source a second hand security module. New one over £400!

 

ZF 6HP26 is fitted to all 4.2 liter cars.
A slight clunk downshift 2 to 1 isn't unusual - if it slight, almost light driveline backlash. But a harsh lurch is an old known issue that you can easily find here or on the internet if you search for ZF lurch. It is resolved by a TCU reflash. I had the dealer reflash my TCU for a different issue, was about $240 in the US.

Search the forum for info on transmission fluid changes. There is a lot of info and different opinions on costs, DIY, and what kind of fluid is acceptable. I had the dealer change my fluid with jaguar liquid gold and the magic anti bark elixer, with new pan/filter, sleeve, pan bolts, all for about $1000 if I recall correctly.

 

Thanks for the info. Steve. It would appear to be a not uncommon fault with this gearbox.
Price for oil change in the UK would appear to vary from £150 to £400! As for the oil it would appear the the same oil is used in Land Rovers, but at a fraction of the price. Ho Hum.