My '87 does that, too, at idle with a warm engine. I assumed that it was a failing or dirty electrical sender for the electrical oil pressure gauge. The sender is fairly expensive so I was holding off. I haven't checked the two little oil filter o-rings and need to -- on the '85 they had turned to hard plastic.

Jeremy

__________________

"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