zero oil pressure (at idle)

Hello all,
after my engine gets warmed up (~200 F) the oil pressure drops to zero when at idle. The idle is erratic also, kind of fluctuates. This engine is fairly new (rebuilt), aprox 6K miles on it since i bought it from NAPA.

At startup the oil pressure guage climbs up to 1/2 (30psi i think) and while it is cold it idles pretty well. But while im just driving down the road with the engine warm, the oil pressure gauge is at about 1/4. But when it idles (hot) the oil pressure falls as the engine settles into its rough idle. Im not sure exaclty what to do or look for or what to do.
Any advice is appreciated, Thanks

You run it at 200? That's a little hot, no? Check your oil pressure sender unit first. When I had my '92 RS I had about 5lbs at idle, it was pretty scary. You could always use a heavier grade oil to boost it a little.

Check the level and condition out :eek;

200 is fine, the car is supposed to run 210-220 in stock form.

Check the level and condition out :eek;
wright, i am assuming that you are talking about the level/condition of the oil, both of these are ok since i have changed the oil and filter recently and the problem still presists.
I belive now that this is more of an idling problem rather than oil system prob since while its idling @ zero psi, i can give it some gas and the pressure goes up immediatley to the level at which it was at while driving, 1/4 of the way up on the gage showing me that the system is capable of providing pressure to the engine when its running properly.
SG007 i dont think it is my sender unit since it reads the correct oil pressure at other times and the gage freely fluctuates up/down through out normal driving. I am running 5W30 grade oil in it as per the oil fill cap, perhaps thicker oil would alter the pressure?

i'm not even sure what goes on with the oil pressure gage, i was told that the gage doesnt read how much psi it takes to pump thru the pump/lifters etc, but rather, it measures the ammount of pressure b/t the main bearings and the crank? is this correct? what goes on when no oil pressure is reading on the gage?
going back to the idling issue, would the fact that there is very little back pressure change the way the oil system functions? since i am running headers/flowmaster the smog system is way out of whack i.e. the egr valve not functioning properly. just wondering if the oil system runs off vaacum as the smog and other systems do...
thx

No I don't think your smog and exhaust is the problem, but try the heavier grade oil if it makes you feel better. That's all I can think of for something like this...I mean, I had real low oil pressure in my 3rd gen too...until I spun a bearing and then all hell broke loose. Take it to a garage, maybe they know something we don't. The other guys around here are pretty helpful, I'm sure one of them could shed some light on it. There's also camarosource.ca, they have a pretty huge forum too, check them out.

Well, other then verifying that the sending unit is correct by installing a mechanical gauge:

Since it's a crate engine, perhaps it is too early to run a thicker oil due to tight clearences.

Perhaps the oil pump installed is defective. (could play into the ikdle issue)

Perhaps the main caps are torqued too tight (would also explain a little on the idle issue)

Your cold idle pressure should be up there 40-50psi then drop out to 30ish +/- a few psi when warm.

today i looked closer at the pressure gage today whilst driving and cold it settles right around 30 psi idling or crusing. once it gets warmed it drops to bellow 15, right around 10-12 i would guess while crusing, and while idling the enging kind of 'revs' itself up and down a very slight amount sometimes bringing the pressure up from zero to 10 or so.
should i be nervous sitting at a stoplight starring at the gage showing zero on the oil pressure?? what exactly is going on or not going on when the oil pressure is @ zero?
thanks

edit: as for being a crate motor, my neighbor asked me shortly after we put the motor in if my oil pressure was really high and i said yes since it was up at around 60 psi for the first few months or so after it was installed. what does that tell me, that now that the motor is 7000 miles old its dieing on me?

should i be nervous sitting at a stoplight starring at the gage showing zero on the oil pressure?? ?

I would be. You really need to verify is it is indeed that low or is it another case of a flakey gauge, wiring or sending unit. What oil did Napa recommend you use? Did you change it out at the prescirbed initial interval?