Coming home this evening, my oil pressure indicator light came on. Hearing no expensive noises and with just a few miles to go, I made it home safely. I found the engine oil a quart low, so I added a quart. Cranked up, and the light went out for a few seconds, then came back on. I just finished reading the Bentley manual section, and plan to check the pressure sending switch. The photo of the 528e in the manual was not too clear, is the switch accessed from above the oil filter location, or below it?