I am wondering if....
By observing the gauge's usual behaviour, and either oneself or a passenger keeping reasonably regular observation of the gauge, one might get a timely early warning of any impending oil pressure disaster? (
Pleonastic tautology admitted.) As Angie says approx, a gauge gives more information than a warning light. Oil pressure disasters are I hope rare....but must be very expensive, So the expenditure on the gauge could be at least very reasonable indeed.
That real reason might save one from needing an engine rebuild? But. And. As a bonus. A gauge must surely look reassuringly impressive.
