Hey Cuda and Donziman, txtaz here from Donzi.net. How ya doin?
I have used Amzoil in my cars for years and very happy with it. Between Dad and I we have 8 motors running with it. We use it in everything, motors, tranny's and diffs. We have noticed a big difference in engine and diff life. I plan on putting it in the Donzi as soon as I flush it very well with the normal stuff because of poor maintenance by the previous owner. Poodle sent 3 cases so I can change every 10 hours and an oil change kit (drain hose). After that I'm changing all fluids to syn. It's more expensive, but I think it's good insurance.
Wes

I had lower oil pressure when switching to synthetics figuring it was flowing better with less resistance and about the same temps. Is that criterion for using one over the other?

I've been told by every engine builder to run normal 20-50 for the first 50 hours or so to assure the rings seat properly. After that Synthetic is better if your that picky or running big temps and HP