I just bought this 2004 trailblazer 4.2L with 170K miles. Truck has been regularly maintained. Every 3,000 miles it went in for service. Trans fluid has been changed twice in 170K miles. I don't know what brand of fluid though.
The transmission seems to kind of "slide" into the gears especially 3rd gear when accelerating aggressively. It slides into 3rd gear and within a second or two I feel it engage solidly into gear (solid hook-up). BTW - no trans slip trouble codes.
I think this "soft" shift might be normal for what folks would consider "smooth shifting" but I don't like it
I plan to change the trans fluid and would like to have "firmer" shifts. Can I use a fluid like Jeggs quick shift or B&M trick shift to improve my soft shifting without sacrificing transmission durability/longevity?
OR
should I just put just put Dextron VI synthetic in and learn to live with it?
Thanks for your comments

 

Stay with a Dexron VI fluid and forget about the specialty fluids. If you want to add something, the only thing I would consider adding is Lubegard Red. I have used it and the transmission seemed to be a little more responsive when shifting. Also, Lubegard Red is the only transmission fluid additive I know of that is GM approved. It is not snake oil, and the proper dosing is 1 ounce of Lubegard Red per 1 quart of transmission fluid.

Here is a link to the product:

https://www.lubegard.com/products/red/

Good Luck!

 

Thanks for the great recommendation chem_man! I just ordered Lubeguard Red. You mentioned to stay with AC Delco Dextron VI - regular or Full Synthetic?

Also, speaking of chemicals. The power steering seems stiff (a little hard to turn) and doesn't quite self-center all the way after a turn. I was thinking the local garage that did the "every 3,000 mile services" on this Trailblazer used generic fluids. I removed the fluid in the reservoir and put in Delco PS fluid. It seemed to help just a little. Do you have any thought on this? Maybe a lower viscosity fluid or a full synthetic PS fluid or even Dextron?

 

You can use Dex VI. It's all synthetic. I do the same on my 24 year old K-1500. Haven't had any PS issues.

 

You do not have to use ACDelco branded Dexron VI or power steering fluid in your vehicle to get the full benefit. There are several brands of Dexron VI on the market and in order to use the Dexron VI name and spec, they have to be licensed by GM - similar to how motor oils pay a licensing fee in order to use the Dexos specification. As far as power steering fluid goes, I use either a store brand, Valvoline, or Prestone fluid that meets the GM spec, and is on sale. I usually purchase a gallon at a time for my "fleet" of vehicles.

Also as oilcanhenry mentioned Dexron VI transmission fluids are pretty much all synthetic, but a few brands used to be synthetic blends. As long as it meets the Dexron VI spec, you'll be fine whatever brand you use.