I have a 2012 gmc seirra 1500, in the book it says I should flush my fluid at 97k, I have heard all kinds of bad things im just now hitting 100k and Im dying to know if I should or not.

We normally do them every 60K

Do you think it would effect my transmission at all?

Has the fluid ever been changed? I would absolutely change the fluid and filter and obviously upgrade to Dexron VI. That'* a lot of miles for trans fluid. I don't really believe in the old tale that if a trans has miles, don't change the fluid or it will ruin it. I have had many high mileage 4L60'* apart and if there is a lot of sediment in the pan, it may already have a problem. However, with that many miles, you are bound to find some sediment. If your trans has a hesitation as you say, it may be on it'* way out, but changing the fluid may help and extend the trans life. I have a 2002 Denali XL that has 168,000 miles and I've changed the fluid 3 times so far. It still shifts perfectly and shows no signs of the 3/4 clutches going bad as sometimes happens with high miles on these. Give it a try - It should make for a better shifting transmission.

It'* more about PM than as a way to correct a problem. You don't want to wait until you have a problem or it'll need a lot more work.

I have heard the myth about "I changed my trans fluid and then the trans went bad" for years. It does not make sense. Transmissions have very small passages & need lubrication and "gunk" cannot hold a trans together and keep it shifting properly. Also, over time, the fluid breaks down and cannot hold up to heat which will kill a trans eventually. If you drop the pan & it'* full of sediment, it'* probably on it'* way out anyway, but changing the filter & fluid may extend it'* life. If your truck has the 8L90 8 -speed trans, they are actually very durable and it should last a long time, so go ahead and change the filter & fluid.

I'm not sure about the changing fluid causing problems. I've had a few tranny'* that we got and were Way, Way overdue on service and after servicing they have problems shortly thereafter. Some believe the dirty fluid is thicker and therefore will not leak around seals and valve bores as easily as the fresh fluid. I can only say if it was that bad it was going to puke before long. When we had people come in and tell us......."I need my tranny serviced".......I ask.....while I'm pulling the D stick out......Are you having a problem....and see this nearly black burnt smelling stuff (can't really call it fluid).......It seems to be slipping or some other problem......95% of the time people forget about their tranny'* until they start to have problems.

I would also recommend a trans pan drop w new filter & Dexron VI fluid. Friction modifiers do break down over time/mileage and some new fluid in there is a good idea IMHO.
It also allows to clean & view inside the pan for any particulate matter.

Excellent advice, as well as from the other posters.
I would like to add to the O.P. that the 'flush' procedure is an aftermarket and less reputable dealer 'service' they are selling. It is not an OEM approved preventive maintenance procedure to run solvents or a universal, non approved fluid or additives through a transmission.

The usual recommended change is 100K miles, unless under harsh conditions, like driving in mainly hilly areas, constant stop and go traffic, towing, etc., then it should be done around 50K......

Power flushing is better because it removes all the fluid from the system, as opposed to a pan drop, which can leave up to 4 quarts in the system(mainly torque converter)......

So at 97K, a power flush should be no problem.....

However, when you have a vehicle that is say, 150K or more, or older than 10-15 years, and you have no idea of it'* maintenance record, because you are not the orig owner, that'* when the debate of to flush or not comes into play.....most would tell you just a pan drop and filter replacement should be done.....the problem is the additive that is added which can loosen up crud in the system(get trapped in valve body), and if seals become hardened, the pressure flush can have an effect on them, causing problems down the road......

I personally recommend a flush every 50K, with no additive for "cleaning"......

I posted a question about the filter procedure done by shops, that apparently got posted in the wrong post....

What is the usual procedure in shops? I have seen three ways:

1. Flush with no filter replacement....

2. Replace filter, and then do flush......

3a. Flush.......drop pan, capture fluid(reuse), and then filter.......

3b. Flush.......drop pan, filter, and then top off with new fluid(don't reuse fluid).......this makes job more expensive because of the addition of 7 quarts to bill.......