XD-50 or XD-100 for '94 Vindicator 200?

[luckyinkentucky]

Out of the XD-50 or XD-100 which would be better for my engine? It's a '94 Vindicator E200STLER, and I usually run it at WOT 90% of the time. I realize the XD-50 is a Synthetic Blend while the XD-100 is a full synthetic required for newer ETEC engines. Would it benefit my engine to run the full synthetic, or XD-100?