[drymite]

Low oil consumption
I have this random smoking issue that happens
OE turbos 12000km car jus hit 290k km
Compression test all in spec didnt do a leak down.
So no smoke on cold starts. When engine is partially warm or operating temp i can hold the rpms at 1100 no smoke.. drive around no smoke on decel. I get the slightest smoke when im waiting a stop sign long enough... randomly when the engine usually is at half operating temp around the 160-170f i would get a bit smoke on decel from only the driver tail pipe: but after its warm and i do a WOT no smoking at all... only once i noticed on wot i got a cloud of blue smoke . But the same day i drove 3 hrs and no smoke at all. Im wondering could this possibly be a kinked oil drain the intermittently doesnt drain properly. My next suspect is the BMS PCV valve and the Gates PCV hose....
Mods
VRSF catless DPs
BMS intercooler
VRSF chargepipe
MHD stage 0 currently since turbo swap.

I couldnt find much reviews about the BMS pcv valve i was only able to figure out that Rb pcv valve uses a toyota part made to fit the N54 while BMS is completely aftermarket part. Also not sure of how good "gates" parts it was the only pcv hose i could find locally A year ago.

No codes aside from the catalytic efficiency codes.

[iqraceworks]

What turbos...and how many miles on them? Seems like 90% of the time...smoking issues are from weak/bad turbo seals. Very common issue. They suck in oil under high vacuum...like idling and decel, and run great under WOT when they are under pressure. They can smoke sometimes...and not others.

Nobody really wants to hear it...but that's usually the issue.

[drymite]

Engine is at 290k km- 180k miles
OE Rotormaster CHRA that are supposed to "meet and exceed oem standard " i swapped the CHRA my self and upgraded the wastegates on the housing. I had the same turbos on my last e90 335i with 30k kms so roughly 20k miles. That had no issues but got rear ended by truck totaled .
The current ones have only 12000km on them... its just weird how i can go like a weeks at time without any smoke from the tailpipe. Intially when i got my e92 that i currently daily with blown turbos it would puff heavy clouds non stop... one thing i noticed that my Uro valve cover with gasket. That i installed 10 months ago. Torqued with 1/4 torque wrench inch pounds to spec. Seems to be failing it wasnt leaking all year until recently and there was oil covered all around all the coils n plugs and its caking the rear inlet with oil . Thats why i was questioning if anyone had issues with a BMS pcv valve and gates pcv hose. Or maybe the uro gasket is just trash i read couple post that say use a elring gasket..

[GSB]

My car was doing exactly the same on a stock engine with an "upgraded" PCV valve, which turned out to be too restrictive. As the N54 engine ages, or turbo boost is increased, blow-by gasses increase. Failure (or restriction) of the low-side (vacuum) PCV valve results in those nasty pressurized crankcase vapors taking an alternative route... through the high-side (boost) breather/flapper, then through the turbo, charge-pipe, intercooler, diverter-valves, throttle-body and intake manifold. I've found puddles of oil throughout ALL of those intake components - twice. Those puddles are occasionally gulped into the cylinders, causing smoke, oil-caked valves, and reduced performance.

The lack of sufficient vacuum in the crankcase also causes the rear main crankshaft seal to pop and leak all over your garage. Furthermore, since the N54 low-side (vacuum) PCV route is integrated into the valve cover, we have no way to access it to install an oil catch can, and even with a perfect PCV valve, all of that oil gets sucked into the intake, again causing smoke, oil-caked valves, and reduced performance.

An RB Turbo external PCV adapter is the best answer, with an excellent PCV valve, and the opportunity to install a good oil catch can system. I now have no oil in the intake and no more smoke.