Yesterday i was driving in scorching weather (32°C / 90°F) and after around 15 Minutes of relaxed driving, when the oil reached around 105°C / 221°F i noticed the oil pressure was dropping when standing and idling (crossings, traffic lights, etc). Idle RPM was normal but the gauge showed between 0.5 - 0.7 bar / 7.25 - 10 psi.
I am sure this is not a normal oil pressure for a rotary, it most certainly isn't for a piston engine. The oil pressure was normal once i just touched the gas lightly (1000-1100 rpm) and sometimes after standing for around 15 seconds the oil pressure would go to 1.0 - 1.1 bar / 14.5 - 16 psi again - which i would consider normal. Oil level was right on the edge to F on the dipstick.

I am running a mostly stock engine, rebuilt 10.000 kms / 6.000 mls and 5 years ago, compression in april was between 110 and 115 (corrected) on 31st of march.
Stock twins, even if the return line of the rear one is leaking they are both working (until they hopefully get thrown out for a single soon)
Most emissions stuff is removed
Oil Pump takes 2T oil from a seperate tank and i add in a small gulp of 2T in each full tank.
Engine Oil is Liqui Molly 10W-60, last oil change was a month ago including a new filter of course.

I could imagine it being an issue with the sensor, which would be of course my preferred outcome - for that i would have to find it however...
If anyone else has ideas and suggestions, let me know, i am happy for any ideas that could bring me to fixing this issue

 

If you are going off the factory gauge. That's not going to be accurate at all, especially in the lower rpms/pressures. For a true reading you need a quality aftermarket gauge.

Many of the factory Oil pressure gauges don't work at all, or work off and on, especially in the idle ranges. My factory one is currenty doing this. Sometimes its a bad sender, sometimes its build up in the sender port etc.

 

My bad, i missed important information: I don‘t use the factory gauge but an aftermarket one (Prosport i think). However i don‘t know yet where and theough which sensor it gets the pressure.
i will try to locate the sensor tomorrow.

 

2 things.....

First, your oil temps should not be that high. You either need to upgrade your coolers or go to a heavier weight oil.

Second, the fsm shows how to check oil pressure and there was minor discussion on it some time ago. If i remember right, the pressure reading is to be checked at 3000rpm. If its above whatever value stated in the fsm then it passes. It makes no mention of idle or any other condition...... or something like that

Since your temps are WAY too high, naturally oil pressure will be lower. Your car requires corrective action with either heavier oil or an oil cooler upgrade.