Dealer uses Mobil Delvac but I was thinking about using Rotella. Is one really any better than the other?

Many thanks...Happy Holidays!

You'll find fans of Delo, Delvac, Rotella, Amsoil, etc. Personally, I use Delo (non-synthetic), but Delvac is right there at the top of the "best" list, too. The synthetics in these brands are excellant, especially if you live in a cold climate.