Hey guys, I'm coming up on my first service for my differential in my 300, and the shop where I work has a contract with Valvoline, so I can essentially Change my oil for free with any of their products as well as differential services. My question is does anyone have experience with Valvoline Differential fluids? Do you recommend? I know most will say of course because its free. But I'm hard on my vehicle and like to take care of it, free isn't always appropriate. Thanks in advance.