Here is a link to the same discussion over on the HAMB:
https://www.jalopyjournal.com/forum/...e-gauge.31196/
One fellow mentions something that I was thinking about re air in the line: It can act as a shock absorber if there is pulsing of the supply. Now that is not really a big problem on the engine oil pressure system, but I do run into it on well pumps and in some hydraulic and fuel systems. There are dampers/accumulators that can be installed to counter this.