low oil pressure at idle? (warmed up)
 

for whatever reason once the miata gets to normal operating temp the oil pressure will drop at idle. it has went as low as 10lb according to the factory cluster. once i get it back under load it goes up to the normal 30-40lb. on a cold start it stays at 40lb at idle, though.

is it possible the gauge is just retarded or is there something i should be adressing?

maybe i'm just retarded.

Oil and filter type? Checked the oil level?

the oil is basic 5w30 castrol syntec. the filter is a fram. the oil level is fine.

Clean the electrical connector on the OP sender with some emery cloth and then spray a little tuner cleaner into the connector on the wire and plug it on and off the sender a few times. If the electrical connection is bad the gauge reads low.

On my Autometer gauge when warmed up I'm a little above 10lbs at idle, and that for every 1000 RPM the engine goes up, the pressure goes up by 10lbs. So 2000 RPM is 30lbs, 3000 RPM is 40lbs, and so on, and then the pressure starts to taper off in the higher RPM range. This is on my brand new engine, my OEM engine acted the exact same way. I know it's always time for an oil change when the pressure starts dropping lower and the oil temp goes higher than normal.

strange, i've never owned a vehicle that's acted this way. i mean, the car runs fine and does the exact same things that yours is doing. i may as well go ahead and change the oil. should i go with something like a 10w30 this time instead of the 5w?

Swap out the filter to a Wix or Purolator and report back, Fram filters suck and have been discussed numerous times on many forums.

warm spec for oil pressure is around 45-55 at 3000 RPM.

that's about what i'm at at 3k. just scared me when it was dropping to lower than 15psi at idle.

yeah. i know. and now that i think of it, my filter isn't a fram, it's a NAPA, even worse. but, i needed a filter and oil and didn't feel like driving 30 miles to get it.

Napa or Napa Gold? If I remember correctly, the Napa Gold is a Wix filter. You get used to seeing 10psi at idle, or I have. When the lifters start ticking at idle, you know you need to dump a half a can of seafoam in the engine, drive it around for a mile or two, and change the oil. I run 5-50 Castrol Syntec in the summer as Mobil 1 never keeps the lifter tick at bay after a good sprint.

The Napa Gold filters are indeed made by Wix.

yeah, it's a napa gold.

if you are worried try heavier oil. I ran 5x30 and after hard driving i would see under 30psi cruising on the highway at 2500. After i put 10x40 oil its all back to normal. 40-55 cruising and 15-20 high idle.