With a "real" gauge tee'd into an oil line, you will find the cold oil pressure to be on the order of 70 psi and even hot the oil pressure will be 50-60 psi with the engine above idle. The factory gauge is more of an "indicator" than a measuring gauge. As long as it pins high at cold idle and stays there while driving you're OK.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970