A few air bubbles in an oil pressure gauge line are not a problem. If you had a copper line, you just wouldn't see them, although they're always there. Getting OCD about a few bubbles is like lying awake at night worrying about why the faucet in the kitchen sink isn't dripping! Low oil pressure is virtually always caused by excessive clearance at one or more connecting rod or main bearings, or too-thin oil. An oil pump must supply more oil than the bearings need for pressure to rise at all. If it was possible to supply oil to the bearings at precisely the rate it leaks away, the engine could be adequately lubricated with ZERO oil pressure. That's not practical in real life, so oil pumps are engineered to provide an excess of oil volume. There is a spring loaded relief valve to prevent hydraulic lock and engine stalling. (Yes, I've seen that happen) Oil pressure is a "safety factor"- - - -whether it's 5 pounds or 50 pounds is immaterial. Excessively high oil pressure simply overstresses the distributor drive gear, which also runs the oil pump!
Jerry
