Oil pressure drop

All

The oil system is designed to work with air pressure, ambient, over the oil as it is a vented system via the oil tank vent.  At 1 bar, 14 psi approximately, you see what you call "normal" oil pressures.  As you climb to altitude this ambient pressure drops, this directly affects your oil pressure.  At 10,000 ft you are losing about 5 psi just to the altitude change.  There may be some issue with how your oil tank vent is working, into the wind or dumping into a low pressure zone, that could affect it also.  

Cheers

Have you contacted a Rotax service center like Lockwood to see what they say?

It’s pretty standard. not facing the wind and not clogged. I have the Bypass opening as well. That’s not it. 

Yeah. I visited Cierva at Petaluma . They thought it might have been a slightly kinked oil line, but that wasn’t it (we replaced it). I am planning to go back for further inspection, just wondered if anyone here has more creative ideas about what we can check.