so I'm at 142,000 and my tranny is definitely in need of a fluid change seeing as it was last done at 60,000 miles.. Do I flush or just have it drained i'm being quoted for a change at infiniti for $179.00 and at an Auto Tranny Specialist in my area for $89 with Matic J fluid.. should I have some lucas treatment added into it also?? I put it in my 02 maxima back when I had it and it really smoothed out the shifts.. **right now I have a hard shift in manual mode from 2nd to 3rd gear!!

How does your fluid look? black?

I'm more in favor of gradual partial drain/fills than a total flush.

^^Me as well. And don't stress about the 2-3 hard shift, it's normal for the 5ATs. After my tune and exhaust, I can chirp 3rd gear in MM if I time everything just right on a stock tranny.

I hope it stays strong, I mean they are carry over Q45 trannies! Maybe it's the weather changing but it feels like it shifts different in auto mode

As stated above, do a gradual change as the clutch packs in the trans have become accustomed to the wear materials in the current fluid. If you do too much at one time you risk slippage and destroying your trans. I don't like flushes, but if you had regularly maintained your trans you could do a flush.

I would drain and fill 1 time during each of your next 4 oil changes. This will take between 3-4 quarts each time, so buy 4 to be on the safe side. When you are finished with these drain and fills you will have replaced close to 100% of your trans fluid over 15-30k miles, depending on what mileage you change your oil.