Transfer case loading and unloading making noise-wrong fluid

I have a 2004 pewter colored gmc yukon denali with approximately 94,700miles on it, that recently sent me a “service ride control” warning message where my odometer milage usually appears. I took it to the dealership and they found a broken right front position sensor that could be replaced and reprogrammed for $390 or I could live with the warning and keep driving my car as is. They told me that I would not be in danger driving the car with the bad sensor. I had mentioned to them that long before the warning light came on (2weeks ago) that approximately the past 6months I had been hearing a rotational noise from the left front when driving 20mph with my window rolled down. They checked wheel bearing, u-joints, axles which were ok but found the transfer case loading and unloading making noise. They said that they found the wrong fluid in the transfercase and front differential. They said that there were lots of metal filings in the fluid and that it needed to be flushed and have the fluid replaced. It would cost well over $100 but I appear not to have gotten that estimate in writing. JUST 6 WEEKS EARLIER (92,700MILES) I HAD HAD THAT DONE WHILE GETTING AN OIL CHANGE AT A PLACE THAT SPECIALIZES IN OIL CHANGES (SLOGAN IS “THE ONE YOU CAN TRUST”). Looking at my bill from Oil Can Henry’s, it says transfer case service 49.99, red line syn gear box fld special fluid charge 20$. Question is who should I take my car to and what is the right fluid for the transfer case? how can someone tell that it was the wrong fluid? What is a flush? Maybe Oil Can Henrys forgot to flush when they replaced the fluid. I am thinking that I should go back to Oil Can Henrys and tell them to replace and flush the fluid with the proper one at no charge to me because they messed up the first time. Maybe the old fluid that they replaced was making the noise and then the new wrong fluid didn’t fix the noise, or maybe the noise is something else?

Thanks for your time, I look forward to your answer.

BEN

me again. when they “the ones you can trust” change my oil every 3000 miles they use a more expensive motor oil- synthetic blend. They tell me that is a better lubricant than regular motor oil and I believe that I have heard that it need only be changed every 20000miles vs the usual 3000miles but they bring me in every 3000miles because they say that the filter is only good for 3000miles. Shouldn’t I just use regular motor oil then, since I am changing oil every 3000miles? They said no because “you can reach through a barrel of this synthetic blend oil filled with ball bearings and regular oil is not as slippery and you would not be able to put your arm down to the bottom of the barrel of ball bearings if it was filled with regular motor oil”

If you go back to Oil Guy Harry who put in the wrong fluids in the trasfer case and differential, they will tell you it wsa the correct fluid and put the same junk back in. Get the proper fluids from a GM dealer and hope you transfer case and differential are not junk already. You can tell the wrong fluid by the color, and weight of the fluid.

Motor oil is the same requirement for many cars and an oil change place can stock a few types of motor oils and serve all the cars that come in. There are many more types of transmission fluids, differential fluids, transfer case fluids, brake fluids, etc. Rather than stock all the different types they go with “generic” stuff that is not specific for a particular manufacturer’s cars and trucks. It would be too much stuff to inventory all the special fluids. If you must use a “quickie oil change” place stick to the oil change only. Don’t get sucked into all there other services. It is profit for them and headaches for you.

If you change your oil every 3K miles I see no reason to spend money on synthetic oil. Conventional oil is fine. If you drive with a trailer hooked up to your truck all the time perhaps then I’d consider a synthetic.

Thank you uncleturbo!