I didn't wanted to be so blunt as to suggest to run the oil level below min due some attitudes here. However, I played with oil levels on our machines and marked a new minimum where they breath least but maintain the level-some 100hr to 100hr. I had various discussions with the factory and 350 team at Marignane and they admit its a known problem but due certification can not change the level indicator. On the 365 its even worse as shes got the same tank with the same marking yet the engines are below the reservoir level so you need to chk quickly otherwise halve the reservoirs oil is in the MO1.
The key to the ARRIEL oil system is the breathing system. On machines that work hard and hovers a lot at MAUW I check the breather tube of the MO3 rear bearing regularly and clean it out-one just have to respect the AMM procedures whilst doing it carefully to avoid disaster. Oil mist or wetness on the rubber external tube running from the breather is a sign of breathing issues whether it is too much oil or a dirty or partially blocked breather tube internally or externally. The return line tube on the MO3 rear bearing can also cause major issues if partially blocked as the only place to get rid of the oil is threw the breather tube then. First sign of trouble will be coking of the MO3 rear bearing breathing tube and of course the flow check on the 600hr.
For machines that spend their life hovering a black tailboom is a given. Not all the oil from the MO4 bearing is scavenged and a very small amount gets dumped. In forward flight it spares the boom but in hover not.