Chrysler Repair: oil light on at idle, chrysler sebring convertible, chrysler sebring

Question
1999 Chrysler Sebring Convertible JXI 2.5L 6v

Rebuilt motor due to (idiot light)= oil light would
come on when stopping and when moving it would go off,
it did have 201,000 odm at the time.

So I had it motor rebuilt last year 11/10.
1 year Warranty will expire 11/11.
Now, The (idiot light)= oil light is coming on in same
way, stop on and go off, again.

The new motor only has 6,000 odm on it. First oil change
done and second would have been due now.I have not had it
done yet when the light started, but oil level fine.

I not so sure how much I trust my mechanic and he talks down to me as if I don't know what I'm saying. Plus He told me that the oil light is really not that important/faulty cause he said I put to much oil in, and well the oil light keeps coming on, and I felt there wasn't enough in it when I checked. proir to my motor being blown in the first place. I also feel i paid way to much for my rebuilt motor. So, I need a second opinion.

Thank for any all help/suggestion you can give me.

Maria

Answer
Hi Maria,
What is the number/'weight' of the oil in the crankcase? The oil pressure at a given rpm, in this case idle speed, depends upon the weight (viscosity) and the temperature of the oil. You probably notice the 'on' light issue when the engine is warmed up, but not when it is cold/just started in the morning, correct?
The scientific way to check the oil pressure is to remove the on-off pressure sensor switch next to the oil filter and insert a pressure gauge in its place. At idle the pressure should be at least 6 pounds per square inch, and at 3,000 rpm it should be 35-75 psi for that engine. If it meets those specs then there is no risk of damage. The light coming on at idle is very common and generally not a concern, but if it ever happens when the rpm is above idle then I would stop the engine promptly to investigate.
If it meets those pressure specs then the reason that the light nonetheless is coming 'on' could be that the on-off pressure sensor is pessimistically reading low. So you could replace the sensor and see if that solves the problem.
Another way to likely eliminate the troublesome light would be to increase the 'weight' of the oil one step for example if you are using 5W-20 replace it by 10W-30 when you next change it. The increase in operating pressure will likely cause the light to stay off at idle.
This is a very common problem, so you can try any one of these three approaches.
I don't like the way the mechanic spoke with you about this. So if you don't trust him I would consider the weight change first, then buy a simple pressure gauge and check out the pressure and if it passes the tests, then replace the sensor.  The sensor screws into the side of the engine block  on the side that faces the front of the vehicle, just above the oil filter.
While the engine is under warranty you might want to check the pressures with a gauge so that if they are too low you can ask that the problem be repaired at no cost. Go to another shop or buy the gauge at a parts store. The threads are tapered so the connection/switch needs to only be tightened in firmly but not torqued to any significant degree to avoid cracking the block.
Roland
PS Sorry for the delay in responding to your question but I just found it in the 'pool' to which it had been referred by Kevin. Please 'rate' this answer and consider giving me a 'nomination' for 'expert of the month' if you feel that I warrant it. Thank you.