Need help with oil options

With a different block, I would go through the break-in process again. Some may consider it "splitting hairs", but it is possible for the lifter bores to be off from the previous block which can change the wear characteristics a bit. Whether or not it's enough to matter depends on the person. I tend to be extra cautious and not take any chances. You have to "break-in" the rest of the engine anyway.

As for what oil to use, changing brands shouldn't matter as long as it's a quality oil with the proper additives. It's usually better to use an oil with the zinc already in it rather than playing chemist. It wouldn't hurt to confirm what the current Rotella oils have for zinc. These days you can't take it for granted because most shelf oils don't advertise it and have had the content reduced over the years, including diesel oils.

Personally, I use Amsoil Dominator 5w-20 in my race car, but they have a wide variety of oils and viscosities to choose from. They also have their own break-in oil.

[ame]http://www.amsoil.com/techservicesbulletin/motoroil/tsb%20mo-2007-08-08%20flat%20tappet.pdf[/ame]

www.amsoil.com