SpotOfTea

Sorry first post here. My local dealer is being a jerk. I have a 2003 GMC Sierra 1500 HD 6.0. I recently drained and refilled the transmission with below which seamed to be within the specs of the owners manual. I had some from a SUV I had in the past. https://www.amazon.com/dp/B00T96Q9A6/ref=dp_iou_view_item?ie=UTF8&th=1 It's always had a bit of a whine since I got it hence why I tried to replace the fluid. But then when i was looking up online about the whine I saw that I should be possibly running Dexron VI instead and that GM had updated the specs. Can anyone help clarify things for me I am new to DIY. Thanks