So-I have a 2011-Silverado that I use for a tow vehicle. I bought everything I needed for an oil change and I couldn't get the drain plug loose. It wouldn't budge.(Last time it was changed by the dealer was back in March). So I take my oil and filter down to the local Jiffy Lube and got a whole $2.00 off for my own oil and $2.00 off for my filter for bringing it myself. Anyway -it has 45,000 miles and they tell me it's going to need a transmission service at 50,000 (which is correct for me since I towed my travel trailer 12,000 miles last year-they didn't know that however) otherwise the manufacturer says to change at 100K. Anyway I asked them what Dex 6 fluid they use. He said they use Dex 4 but put in an additive package to make it a Dex 6 equivalent. Does this sound correct? Comments?