ATXSierra

I wasn't aware of the shudder issues and hadn't experienced that yet, however interesting to note the Mobil1 fix. Thanks for sharing. I confirmed with service and on my work order that they did use the new Mobil1 fluid. They essentially refilled because it was entirely empty. Also have not yet contacted GM directly, but my thoughts were in the exact sam place with respect to an extended warranty. With this truck under 30 days old and 1k miles I already have doubts I'll keep past 5/60 if there is not an extended warranty in place. Accessories are never a bad thing either!

Thanks, SS502. I checked trans temp right as I discovered the problem and it was 186. Just got a call from service. The cooler line failed at the radiator. Said it was improperly fastened and/or not fastened? (Sketchy?) Good news is they replaced the line and, hopefully, connected it this time. With new fluid the tech said it "shifts OK" and will drive it a bit more and then confirm its OK for pickup. I like the advice on putting it through the ringer. Fingers crossed.

I've been lurking on the forum for a while, and have gained a lot of valuable information from everyone. I wish my first post was under better circumstances. I recently purchased a brand new 2018 GMC Sierra SLT with premium plus package. I've driven a Jeep for the past several years, and recently brought home a second german shorthaired pointer. It's hard to fit two kennels in a Jeep, let alone all of my hunting gear, so enter the truck. I was thrilled about the closeout deals on 2018 Sierras in my area, and here we are. It is a 5.3L with 8 speed auto. Yesterday I was driving home in traffic at about 50 mph. The truck currently has only 1000 miles. I see smoke out the back and begin losing power. Wound up in the center lane, still have oil pressure and engine is on... no power to the wheels in drive or reverse. Step out of the truck and see a long trail of fluid and then pool of red underneath the truck. I know its transmission. I called GM roadside and got a tow to the dealership in about an hour (kudos GM.) This morning they get the truck into service and initially tell me it is a blown transmission cooler line. They state that they have ordered a new line and will throw that on there with new fluid and all will be good as new. What are your thoughts? I don't know how long I drove before the failure of the cooler line, but anticipate not very far given how fast it drained dry. I've already lost trust in this truck, and curious how to ensure either satisfactory repair or replacement. A new hose and flush, without opening the trans, makes me nervous. What potential damage could happen to the transmission in this circumstance? Thanks, y'all.