I'm new to this GM thing

I'm used to Chrysler'* with ATF+4 that you can only get from the dealer at $5-$8 a quart ).

I just did a tranny service on it and used Mobil ATF (dino) from Costo at a little over $1 a quart.

I was wondering if anyone had a favorite dino ATF for these things.

i always use a name brand...quaker state etc.....

I've had good results with Quaker State Dexron /Mercon.My last tranny service had Castrol installed to the best of my knowledge and it had a slick almost synthetic feel to it.It'* supposed to be a top quality non-syn fluid.I wouldn't use some store brand fluid unless you really know what you're getting.I had a tranny service(actually more than one over the last 5 years) done at Pep Boys using their Proline house brand fluid that supposedly is the same as or made by Quaker State. My Regal (4t65e) was shifting like a dog.I replaced it with Quaker State and it firmed up the shifts alot and the car actually accelerated well again.The Proline was only in for about 6000 miles before it got doggy and it looked and smelled like new when I changed it out.Or something else is going on with the tranny.

Currently, my favorite is Valvoline Max-Life Dexron III. (I suspect that it has a very good additive package.)

cant go wrong with AAmco dextron fluid since they do make trans and rebuild them and also test there own product. Also Royal purple has been gettin some good reviews from my job also