Originally Posted by Yetti
I dunno about plenum gaskets, but i have seen the engine sludge up enough to plug the oil return holes in the heads with high miles. after the return holes plug the valve stems are submerged in oil and can't help but burn it. I would start there first.
I was thinking along these lines as well . Does it tend to roll blue smoke if you shut if off for an hour or two then restart it ? Thats oil getting down the valve stems . That kind of miles the guides are getting loose and the valve seals are getting hardened .
Sounds like some one ran Pennzoil in it