I've recently changed the oil and filter on my 84 Ranger 2.8L V6. I used 10w-30 dino oil and filled it in range on the dip stick.
I noticed that after I changed the oil, the oil pressure gauge (on the dashboard) would be in the 'middle' portion. Several weeks later, and now the gauge is hovering over the 'low' portion. Checked the dipstick and it was still filled with oil.
What would be the causes of low oil pressure when the dipstick says there's enough oil?