2007 NNBS 60k Transmission slip after flush.

[dougf]

So, I decided to follow some directions I read on another forum on flushing the transmission in my 2007 NNBS Silverado Z71 with 60k miles. I never had an issue with the trans but wanted to replace the fluid and then eventually do a pan drop with a filter change at 100k.

So, I removed the top line going into the trans cooler, installed a fitting, and with a hose from the fitting into a bucket I started the truck for 10-15 seconds pumping out about 2-3 quarts of the old fluid, replaced, and continued until the fluid coming out was clean.

It took about 15 quarts of Valvoline Synthetic Dexron VI. I then did something I should have avoided, I put a bottle of Lucas Transmission Treatment, the white bottle that prolongs the life of a transmission. I didnt overfill it.

Now when I apply light throttle between 40-50 MPH, while going slightly uphill I get small surging sensation, my RPM's go up and down consistently while It gets worse, to the point where it sounds as if I am hitting the rumble strips on the side of the highway. I get a slight popping, like its trying to catch a gear and it cant grab it. Goes away when I apply more gas and get above 50.

So, im not not sure if my transmission doesnt like the Valvoline Dexron VI, or the Lucas Transmission Treatment, or both combined. I really wish I didnt put the treatment in so I could rule that out. I thought of reflushing with Walmart Supertech Dexron VI (I read its good fluid, licensed by GM) and seeing if it goes away, but throwing away $140 in Valvoline Synthetic Dexron VI really erks me. Any advice or suggestions? Thanks for reading my rant!

[clinebarger]

What transmission do you have? 4L60E or 6L80E?

Any fluid that says Dexron VI on it IS GM approved.

That Lucas crap is NOT approved by GM & should be removed.