Engine breathing - 2004 Stone

I suspect that the breather mechanism on my Stone is blocked. This because at the last two oil changes there has been considerable “mayo” in the rocker covers and sump. I have completed ~2.5k miles since the last oil change which included filter, valve clearances and removal of all the emulsion. The last 2k miles was done in a [very hot] France averaging 250-300 miles a day. Mayo is once again evident on the dip stick.

So, before I start the dissassembly, does anyone have some words of wizdom, experience and a procedure to follow? Ta muchly.

PS: I have been considering “pod” air filters and using a Le Mans style engine breather box, thoughts?

PPS: I am using Motul 7100 10/60 Fully Synthlawries2014-07-01 10:45:12

I had a similar experience with my '01 Stone, so I experimented with the oil. Eventually I settled on a local oil - Penrite Diesel 20w-50 and/or 15w-50 - and had no further problems. I never had any on the dipstick.