Time for Tranny Fluid change?

[Easter]

I've searched the forum, and not really come up with much that matches my issue... this is intermittent, but bugging me, and I'm hoping it's not something serious...

Basically sometimes when the (auto) tranny shifts from 3rd to 4th it has a brief vibration.. one of the few posts I've seen refers to it like going over a "rumble strip" on the highway.. that's exactly what it feels like and sounds like, but it only lasts a second, and it doesn't do it every time.

So would a fluid/filter change and/or flush fix this? According to my dad (who previously owned my X) they had a "transmission service" done at least once and sometimes twice a year.. though god only knows what was actually done.

My X has 131k on it.. I've put 29k of that on there.. so I'd think it's due anyways, supposedly it was changed not long before I got it, but I can't say how long and over a year later my dad doesn't remember exactly when. I'm sort of nervous about doing a flush as I've read posts on here which state it's a BAD idea for higher mileage X's... well more specifically those which have never had fluid changes, but mine has.. so it should be ok?

Also, I'm pretty sure I *could* do this myself, but given that I'm in Texas and it's darn close to 100 degrees by 9 in the morning, I'm not sure I *want* to I'd rather take it somewhere and and let someone else sweat, but where should I take it? I've seen posts advising people to stay away from places like Jiffy Lube, and I think that my locally-owned favorite oil change place pretty much just does oil and state inspections (it's a two bay shop, one for the 10 minute oil changes, and the other for inspections).

Help?

 

[jgilbs]

if, and ONLY if, it has gotten regualr trans service, then you should opt for a full fluid power flush. this will clean out the trans and then you will get new fluid. if you havent had regular service to your trans, this is a very bad idea because the flush can dislodge built up gunk and clog up some other area of the trans, oftentimes leading to tranny death. so I would look into that, but a power flush will run u at least $100. check the fluid color first. it should be red, no traces of brown or black. it should also not smell burnt. if it does, then its time for a fluid change.

 

[Easter]

I checked the fluid last week thinking it might be low (it wasn't) and it was still red.. I didn't smell it though

I trust my dad when he says he's had regular maintenence done, I just don't know *What* specifically was done.. I might check with him and see if all of that was done at the same place, if they could pull up records and I could see.

Basically I'm thinking if it had regular tranny fluid changes, and I've had it almost 30k, it's time.. so if it's had that, then a flush is probably not going to kill it?