Lett me make it simple.
1998 Jeep 4.0 with 125,000 miles on it. Requires an oil change every 3,000 miles on regular oil... and those engines FUCK UP oil but take abuse x4000to die.
Mine... I beat the shit out of my Grand Cherokee daily... BUT I ran Royal Purple every 10,000 miles and no issues, drops in oil pressure, or changes in peformance.
in your case, get synthetic blend every 5,000 miles.