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.
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.