How many miles on the engine?
How many miles since the last oil change?
What weight oil have you been using?
Does the engine knock?
Don't trust the factory gauge, they are not known for their accuracy. Most auto parts stores rent oil pressure gauges: Check oil pressure on a fresh oil change when the engine is at operating temp at 2,000 RPM and at idle, then post the results.
Thicker oil will raise oil pressure, but at the same time, you lose volume. Using oil heavier than 5w30 will oil starve bearings, don't do it. There is a "cushion" of oil between the bearings and the journals. Thicker oil can not pass between the bearings and the journals as easily as thinner oil, as a result, the oil pressure increases trying to get between the bearing and the journal, as a result, the bearings don't receive enough oil.