I took my 2016 Challenger Scat Pack Shaker with 19k miles in for an oil change. My service tech told me the rear differential fluid change was recommended at 16k. I was suspicious, but I okayed it like an idiot. Then I poked around on the net and quickly became convinced that I was scammed. Twenty minutes or so after dropping it off, I called to have it cancelled. After at least 10 minutes on hold, I finally talked to the service guy (or, more likely, the mechanic) and he said it was already done. I told him I thought I was scammed. What do you guys think?