Oil pressure light coming on at idle

On our 65 Valiant we switched to Electronic ignition aboiut a month and a half ago and tuned it down to stock idle specs and since then when the car is at idle the oil light comes on but if I give it any slight bit of throttle the light goes off. I just figured at the low idle we have it at its not getting pressure to the switch and have been driving it with no problems. But my dad got in it today and is saying I shouldn't drive it till I find out the actual reason its coming on. What do you all think? The oil is kind of thin and needs replaced but from my knowledge that doesn't change pressure. My best guess is just turn the idle up a little and it will be fixed, just figured id ask and see if it could be a bigger problem than that.