I have a 6L80 equipped i've had for a bit over 1 year. I've always thought the Wine in 1st gear seemed a bit loud. My son tells me the tranny fluid the put in from the factory is too thin for fuel milage and i should replace it. Any truth to this?

Steve

 

No truth.
Dexron VI trans. fluid has no viscosity choices like motor oils.
I would do a fluid change at 40-50k miles though if your keeping it for the long haul. Use the severe usage maintenance schedule for servicing. I took my '99 Yukon to 200k miles, along with several other cars to that mileage, and sold them running fine with zero trans. issues. My current Tahoe is at 133k and fluid is always a nice red color between changes, and I tow with it also.

 

Thanks very much for the reply. It only has about 10K on it now so its going to be a while before the tyranny needs attention then.