slowly losing oil pressure :(
 

sooo, i usually have about 20psi at idle.. but over the last few months it has slowly trickled to a more unhealthy 15-16psi.. after some searching, i was thinking maybe the o-ring slipped out of place? or something like that.. but then i was thinking that, that would probably have happened quick, and not over a few months? most of the posts threads i've read, deal with psychotic oil pressure. as in surging up, and then having none, and other wild things like that..

i'm not sure where to start looking, or which would be the easiest way of dealing with this problem. i'm going to try and get my pressure tested by a reliable tester, since alot of posts i read said autometer is complete shit.. any input/advice would be much appreciated.

That's still not terrible. Does it increase to good levels when you are driving? General rule is you want 10psi for every 1000RPM.

Yeah it continues to rise and doesn't drop off at any rpm, which would indicate a fucked up. O-ring if I'm not mistaken? I'm pretty sure it is this damn guage

If the o-ring completely blew out, you'd probably lose it all quick. If it were slowly leaking, you may get a slow front cover leak and have time to fix it.

Now the following is just my opinion... if the motor is still stock/was built by mazda, it's not the o-ring. If it were rebuilt in the past, it could be the o-ring. People may have put the wrong gasket/Teflon spacer/o-ring.

Personally, I don't think you should panic. If you are cruising around 3000rpm and you don't have a decent amount above that, I would start to worry.

Yeah motor was rebuilt and streetported by "r&r rotary specialist"?? Idk, but even when if I do start to worry, I don't really know what I would be worrying about??? Because I don't really know what else it culd be besides the o-ring, and other little things like that. Maybe OPR?.. I've read over and over and over that the oil pump doesn't go bad..

Your first move would be to check the pressure with a known good mechanical gauge because your symptoms could just be the result of a failing sending unit.

After my rebuild I had about 25-30psi at idle all the time and around 90psi at 4100 but slowly it went down over about a month or so until I had about 6-8psi at idle and about 30psi at 4100 according to my Prosport gauge. Pulled the front cover to find out the o-ring was totally missing at that point. I found half of it in the pan so I figure it started leaking slowly then finally let go. Hopefully yours isn't leaking but if it is not a hard fix.

Double check it. Dont make my Mistake. I am doing another rebuild now with many parts destroyed due to my Failure to Correctly seat a Front Cover O Ring in the correct way.. the engine lasted 4,000 Miles then Wreacked all the bearings and oil pump Front thrust bearings assembely among other things..

PERMANENT fix - RX-8 timing cover gasket.

Not sure if it works for S5 style front housings, but it works awesome for the S4-earlier style with the wide O-ring land. Just slap on the gasket, no O-ring. IF the front cover ever pushes away, the metal ring isn't going anywhere.

I have pulled the "infamous O-ring" out from under an oil filter before. Unsure how it made it through the oil cooler.

If your engine just developed this low oil pressure, then obviously the shop didn't know about it, so again, have you tried calling the shop that rebuilt your motor? You know, maybe inquire as to parts/gaskets used to try to figure out what might be failing without tearing down the engine.

If the wrong o-ring set was used on the front iron, you could know without ever having to tear down the engine.

I can't believe no one asked this , but what weight oil are you using ? if you are using 10w30 or anything else, you could switch to 20w50 and you will get more oil pressure because its thicker/heavier oil.

20w50 is good for any temperatures that arent freezing or below freezing, ive always run that in my rx7.

Get a nice mobil 1 oil filter and castrol gtx 20w50 see how that works.

You would think so but I haven't found that to be true.

I'm beginning to think my car is a complete outlier though because it doesn't behave like most here seem to.
It's a high mileage (220k), probably original NA and smokes like a chimney with 20w50 in it but runs completely clean with 10w30 in the summer and 5w30 in the winter. Consumption is almost exactly to factory spec, about a quart every 3000 miles.
Oil pressure- read with a VDO gauge- is about the same with either weight oil.
It's weird.

So because I had to delete most of the thread due to the flame war, here's a summary of the suggestions:

1. You need to verify with another oil pressure gauge. The FC gauge is heavily damped, and the senders are old and becoming failure prone. Even a cheap parts store mechanical gauge. One thing to note is the oil pressure sender port is 1/8" BSPT, not NPT. You'll need an adapter.

2. If pressure is verifiably low with another gauge, then you'll need to check:

a. Oil bypass thermo pellet on the front eccentric hub bolt

b. Front cover o-ring. This has the characteristic symptom of a bad or improperly installed o-ring.

Thermowax pellet. Google it