Dear Lynn,

The oil pressure switch threads into the side of the engine block. It has a little port in it to allow the oil to enter the port and open the switch and turn out the light on your dashboard. Theory 1: In the winter when the oil takes longer to warm it may not enter the switch as quickly as warmer /thinner oil would and you see it flicker until full pressure can enter the switch. Theory 2: The wire from the switch is loose or dirty and makes a poor connection as the rougher idle of a cold engine jiggles it. Also as I recall (it's been over 30 years since I had a 122 Volvo) all the dash lights are affected by the operation of the alternator/regulator, but usually all the lights glow or flicker in this case. I really don't think your case involves either of the last two scenarios and even though oil pressure switches are inexpensive and easy to change they are also very reliable.

In terms of keeping your bttery charged it would be better for your car in general if you took it for a half hour drive on a highway rather than let it idle. Engine,oil, brakes, tires, etc. all benefit from regular use.

Hope this helps,
Len