I see a lot of folks sticking with one brand, and saying it’s best to do so, the question I’d have is...what’s wrong with switching every oil change? In the last 70,000 miles on my current vehicle I’ve used Mobil1 EP (3 times), Pennzoil Platinum a couple times, Valvoline Modern Engine a couple times, Shell RGT, Super Tech, Amalie Synthetic, and I used a frankenbrew of Pennzoil/Quaker State/Shell RGT. Intervals ranging from 5,000-10,000 (when using the Mobil1 EP).
If there is ANY advantage to sticking with just one brand, I might actually do it. And it’d probably be Mobil1 I guess. And probably Mobil1 EP (I suppose). It’s easy for me to get, they run their rebates once a year or so, seems to be “good” oil.