Last time I rented a van from Enterprise I had to TALK them into letting me have the oil changed because the oil life warning had been on for a week (had to rent because of junk Ford 6.0 trouble again) IMHO, it's not much of a priority for them-they just figure to unload the vehicles on an unsuspecting buyer, just as the warranty runs out!!!! The "P.T. Barnum" special!!!
My father-in-laws' Blazer had 28k on dealership dino when I reiceived it. Changed it with Vavoline white bottle ran it for 900 miles, then VML blend as the current fill with only a few hundred miles on it. The White bottle after 900 miles was filthy black, the ML blend is still golden after several hundred miles.