Hi!
I own a Sapphire Rs Cosworth 4wd converted to 2wd.
I chance my oil every 2500km, I use MOTUL V300 10/40 engine oil, my oil pressure is good, engine cold 5,5bar (idle) and hot 2,3-2,6bar (idle), when i raise rpm with my engine hot i have readings of higher than 4 bar oil pressure when I pass 3000 rpms.
When I start up the engine from cold there is no engine noise and no blue smoke.
Because of conversion from 4wd to 2wd I still use the 4wd oil dip stick but I fill the engine with oil higher than top(full) mark of the stick. (about 3mm more oil on stick)
Recently I ve had an engine remap and I've noticed that on light throttle conditions my wideband readings are about 11,8 and 13, after a small trip I've made I saw blue smoke from the exhaust when I had left my engine without throttle on a downhill I saw 12,5 wideband reading and when I stoped I saw some blue smoke passing me.
I'have checked my car and I have found the following things:
1. sump/oil pan gasket oil leak
2. oil in hose from of cone filter to turbo (Group A Cone air filter)
3. some oil below my turbo

I have made a rebuild 15.000 km ago and I change my engine oil every 2500km, I'm warming up and I'm letting my engine to cool down when I'm going to turn of my ignition switch.

What do you believe do I have to check first?
Valve stem seals? Turbo? ecu map?