Chrysler Repair: oil light flickering at idle, oil pressure switch, light flicker

Question
why does oil light flicker at 700rpm ??  We have changed oil, and filter, with known brand filter, not a cheap one. Had lucas brand oil additive, installed new oil pressure switch, checked oil pressure with mechanical gauge, had 70 psi at cold, let car run 1 hr. on lift, dropped down to 15psi at idle reved car up to2500 rpm had 70psi oil pressure. what do you think is wrong??is it ok to run this way??? car has 70,000 happened after oil changed we think.

Answer
Hi Lorraine,
The spec for minimum oil pressure is 5 psi on most vehicles, and the idle speed is usually a bit higher but then you didn't specify which engine you have. I would not be concerned about a 'flicker' given that you have measured it to be 15 psi at hot idle and the light flickering. About all I can suggest is to try one more new pressure switch; or you could raise the oil weight one step when you next change it, or don't use the Lucas additive either of which would raise the idle pressure slightly and thus turn off the light at idle without having to buy another switch. In any case, I see no problem with your engine based upon the readings of pressure that have been taken.
Roland