1981 W123 Mercedes Benz 240D adjusting idle speed (and choke tension) will affect oil pressure gauge

although it didn't affect my oil pressure gauge in this video, before i made this adjustment the oil pressure gauge was at the 2 mark at idle. I sped up the idle and adjusted the choke tension as shown in the video until the engine would idle at my chosen speed. i am not a professional! just a lay man learning to maintain my own vehicle :) hope this video is helpful.