I have a 2004 WJ 4.0 with 284,000 miles on it. Unfortunately, the transmission hasn’t been well kept - it’s maybe been serviced one time at closer to 100k. I’m becoming more aware that there’s varying opinion on whether to change really old trans fluid at all vs new fluid is better, etc. Has anyone changed their transmission fluid with a similar interval / milage? Is there anything I should expect or look out for in particular with this? Not looking at a flush, just a drop pan fluid / filter change.



Secondly, I’m trying to weigh the option of using something like Lucas Transmission Fix additive as either:

• a replacement for roughly a quart of Mopar ATF+4 (if I change it)
• or to top off my transmission if I shouldn’t change it

Hoping I could get more precise advice on how the WJ handles this additive (or if it’s even needed at all), particularly in a high mileage / not well maintained transmission. Not having any significant issues with trans right now - at most there can be a slight shudder when initially in reverse sometimes, but I know the wear at these miles can be rough. Thanks for helping the new guy.