Hi all

,
I'm new here & a new camaro owner & coupe cars in general. So recently I bought a camaro 2018 auto transmission (14k mile)
I have noticed the shudder happens from 40mil & up to 80 mil. The way it happens is that it only occurs when cruising especially when the engine is switching to 4V and it goes away when accelerating. Also noticed that it becomes smooth when driving above 85 mil.
Took the car to a dealership & said it they'll not fix it because it was an import car. So they won't fix it unless I sign a waiver in case they break something. So obviously I refused & I plan to take it to a trusted workshop.
So my questions are, what are your suggestions to solve the issue. What steps should I take & what type of trans oil should I use? If anybody succeeded in solving the issue, please share. Your support would be appreciated.
Thanks in advance all.