Recently I've noticed the transmission skipping or lurching into gear at low speeds, especially if in sports mode. I've read about reprogramming the transmission, but this seems like a wear issue since it has never happened before.

Could this be a indicator that the transmission fluid should be changed or the levels too low? I'm on a super tight budget these days, but is there anything I can do that wouldn't be too costly?

I would change the fluid and filter first, not too expensive if you use one of the alternate fluids. I takes 3 or 4 changes to get rid of most of the old fluid, and I am on the third change in 6 mo.
If you still have problems it is probably drum or valve failure, which at 100K is a possibility. As far as reprogramming goes, I have no experience or opinions.

Changing the fluid is a good first step if you do not have any codes.

Not to add confusion but if you look at the symptoms below, especially the second bullet (which are all of torque converter issues) you may move closer to confirming or refuting that what your issue is.

Abnormal Transmission Engagement
• A transmission that fails to shift into gear quickly and efficiently, especially when shifted from park to drive, is normally the result of a bad or dysfunctional torque converter. A lack of torque converter pumping strength can result in slow, delayed transmission engagement.
Transmission Surging
• Transmission surging is a condition where a vehicle's transmission alternates between periods of smooth, steady transmission function and brief, erratic periods of transmission jumping or lurching. This type of transmission function is normally the result of a torque converter that is losing its ability to deliver smooth, constant hydraulic fluid pumping action.
Slippage
• This is another common TC problem, and causes your car to resist acceleration while the engine continues to rev. The most common cause is low or overheated transmission fluid.

Could also be the valve body's main pressure valve, a good auto tranny shop that has the Sonnax reaming tool can re-bore it and install a new valve for probably less than $500.

Any good fluid change tutorials for a 2000 XK8 out there?

https://www.jaguarforums.com/forum/x...deo-faq-50868/

Heres a video from Reverend Sam that should help tremendously.

I looked for that this morning and missed it. Since the 5HP24 has a seperate filter, all you need is a filter kit which includes the gasket. Rockauto offers one for about $15.
IMPORTANT: Loosen the filler plug and break loose the pan screws while the transmission is hot. You don't want to drain the pan and find out the filler plug won't move. If you remove the exhaust cross brace just behind the trans. you have a little more access to the plug.
I followed a suggestion by another member to disconnect the cooler return line at the top left of the radiator and pump the clean fluid in there. I put 6 qts in that way, then started up, cycled through the gears, removed the fill plug and allowed the excess to drain as I waited for the temp/ to rise.
I bought a indoor/ outdoor thermometer at ACE hardware for $10. Just stick the sensor in the fill hole and watch the temp. rise.

So to for a oil change only:

1. Jack the car up on four jack stands.

2. Remove a bolt in the bottom side of the tranny and let the oil seep out (or can you pump it out? How do you get the most of the old oil out?)

3. You use a transfer pump and 7? quarts of Mercon SP tranny oil to fill it as much as you can (this req you to fill it with the engine off first, then start the engine and overfill it?).

4. Start the engine, go through the gears pausing at each gear, leave in park and wait until the tranny pan is 40C, if there is a steady trickle of oil coming out, screw the bolt back on, if not, you'll need to add more oil.

Cost:
4 jack stands $50
Transfer pump $8
Mercon SP 7 quarts 7*7 = $49

Shipping charges approx $20

Total: approx $130

Hi I have found that the ZF transmission in most modern Jaguars start to have issues to a lack of servicing, generally what happens is the oil in the transmission starts to become burnt which then starts a range of faults in the trans and unfortunately it ends with reconditioning the unit. However servicing the trans can remedy alot of these issues and massively extends there life.

I found this blog explains it well.
Land Rover / Jaguar ZF transmission servicing and faults - Pickards Automotive | Car Service Centre | British and European Specilists | Melbourne

jagosaurus- there is a drain plug in the bottom of the pan. The fill plug is on the right side rear and uses a 8mm hex key.

I strongly suggest you remove the pan to inspect the magnets for debris and change the filter.

ZF recommends changing the main pressure valve to a newer version, which may be in your valve body, but I don't know of a way to confirm that. It's not expensive or difficult.

I believe the fill plug can be replaced at 30-50 C. If you start at 30 and have difficulty there is still time. As the temp increases more fluid comes out due to expansion.

http://www.jagrepair.com/images/Auto...%20ZF5HP24.pdf

I believe jagosaurus is long-gone from the forum. I think he ditched his XK8 several years ago shortly after his wife suffered the green shower in it and had a foul-mouthed fit when sending him her phone-recorded video as the green shower was happening. Classic stuff if you've never seen that video (it is posted on this site, search using "jagosaurus ghostbusters green shower" as your search phrase) but be aware, it is not safe for work....

oops, didn't notice we were hitching a ride on a outdated thread.