there is an easy test for valve guide seals.
IF you can see the smoke.
however thinking about this it would fail if the PCV is still hooked up, and the Oil was being sucked in from there.
So here is what I know from experience, mainly with older cars.
When you start or lift off the throttle and when u get back on the throttle the engine will smoke because
1) Oil goes down the guides when standing
2) The vacuum sucks in Oil from head and since you are off throttle, it gets sucked in when you open the throttle. down a nice long hill is a great test.
Oil also can also be sucked in from any gallery that has a leak from intake to Oil (This was on several V8's)
With the addition of CATS minor Oil smoke is no longer a good diagnosis tool, but if its as bad as yours it might help.
Let me also say I am a bit unsure of the valve guides and seals being the issue.
I had issues with GM V8's, Chev's had no real seals, and Buick did but seals wore out quickly. No other issues with any other make ever !!!
So go get a catch can, connect to valve cover, re-route the PCV or block it off, give it a try.
Also I guess if you have the heads off all gaskets and seals will be replaced, new valve guide seals and away you go.
I took down more than one engine just to find a similar problem, start at top, work down, you will see Oil on plugs, ie which cylinders, inside intake, where is it coming from,
For this engine, check for missing butterfly screws, heads off, install new valve guide seals, shop will check for guide wear and clearance ( big bills when you need 16 guides and 15 valves !!! but that was a chevy).
Sorry if this is long and rambling, but i am really concerned this is not your guide seals.
2003 Pathfinder from 2004 SE 4WD
1997 SER 5sp Manual from new Rear Ended 2009 !!
Gone to the Knacker yard...
New ride 3.0 manual RWD not a Nissan !!!
1997 Sentra GXE from new .... Sold 2008
2001 Sunny N16 RHD from new (N16 Nissan Bluebird Sylphy) Sold
Last edited by IanH; Nov 14th, 2012 at 04:40 AM.
Reason: errors typo