I have an 87 sport coupe camaro with the carb. 305. I had a light come on the other day (Choke light) so after doing some investigating I found the choke was working properly but read the light would come on with low oil pressure in some GM models. Not sure if i had one so i installed a mechanical oil pressure gauge in the car using the plug above the oil filter.
Now for the question. My oil pressure when cold is 35-40 psi and after warming up it will drop to 25-30 psi at 2500-3000 rpm and when in gear at idle it will drop as low as 10psi. If i take it out of gear at idle it will go back up to 15-20 psi. I have read that this is normal for a car with alot of miles on it but i want to know what some other camaro owners think.
I was told that the car had 99,000 on it when i bought it and i am now at 120,000 but something is telling me it is actually 220,000. Odometer doesnt have 100,000 dial.
Any thoughts on the issue????
I dont want to blow the motor as it is a daily driver and i cant afford to rebuild/upgrade the motor just yet.

 

Sounds pretty normal to me. If it is bothering you then you could always use a little bit thicker oil to help it out a little. Just don't drive it hard and keep an eye on it. General rule of thumb is 10psi for every 1000rpm you are running so you are right on the mark. You'll know you have a problem if it starts using more oil than normal.

 

Your oil pressure is normal. If you want to be sure about your factory gauge, replace the sending unit, which is a sort of mushroom-shaped thing on a little brass stalk behind, below and to the driver's side of the distributor.

However your understanding of the light is flawed:

For reasons probably known only to the beaurocrats that think that emissions is more important than whether the car actually WORKS or not, the "Choke" light is really the Alternator light. Reason being, the choke is not supplied with power when the alt is not alt'ing, and if the car runs in this condition, emissions limits may be exceeded. Consequently, to satisfy some desk jockey's inflated sense of self-importance, the light is mislabelled.

Yeah I know it's stooooopid, but hey, it wasn't my idea, I'm just carrying the message.

If the "Choke" light comes on, check your alternator.

 

Well that make me feel alot better about having to drive the car daily.

As with the alternator, the car is and has been running great with some difficulties passing emmissions which are fixed now with all new plugs, wires, and vaccum lines and passed emmissions with flying colors, almost non existant. The alternator has been replaced within 9 months and i havent had and issues with it since. But thanks for that tid bit of information will keep it in mind and keep an eye on it.

Just drove it to work and guess what no light so i dont know what is going on with it.