Oil pressure doesn't tell you much about the condition of the piston rings, which control compression, blow-by, crankcase pressure, and oil consumption. Do you notice any blue smoke from the tailpipe, especially after coasting for a while and getting back on the gas? It sounds like you're due for a ring job or maybe more serious internal engine surgery. Try doing a cylinder leakdown test to evaluate how well the rings are sealing. It's a lot more accurate than a compression test.
Jerry
