Oil Pressure on High Mileage 5.3

[DC74]

10 + 10 per 1,000

Yes this is the rule my mechanic swears by, anything too high is taking away from your horsepower

 

[03yukXL]

with 285k miles that's about par for the course. You could up the weight of the oil a bit, but otherwise I would leave it alone. There's plenty of other things that will cause you trouble before that oil pressure causes any kind of issue.