97 850R
Stock, other than a 5 speed swap, IPD lowering springs, bilstein HDs and a few silicone hoses.

325,xxx miles

I purchased this from the previous owner last fall and have been working my way through its various issues as time allows.

After replacing the front exhaust cam seal, which was hemorrhaging, I now burn a lot of oil at idle after sitting for 5 minutes idling.

I'm trying to determine whether I have leaky valve stem seals, a worn out turbo, or ?

I have a nice, tight low mileage 16T from an 04 C70 with ~130K and a spare T5 head I can rebuild.

Is there a good way to tell what the likely culprit is? I've not replaced the PCV but it passes the glove test...

 

a few things to check

1) pull off the intake tube going into the turbo - you should be able to see the vanes via port and can feel around for any end play

2) do a wet/dry compression test to see if the rings are up to snuff (about 150 psi for the turbo engines)

3) not sure about how to test for stem seals - an old school method useful on manual trannys was to go hard in second gear then lift the throttle - if you saw a cloud of blue it meant you were sucking oil past the seals (or rings too?)

 

20 year old stem seals are done.

 

If sitting 5 minutes at idle is the key to it, then I think it's the valve stems and the diagnosis is over.

 

Blue swirling smoke from exhaust on acceleration after coasting down a longish incline is also indicative of valve stem seal issue.