You mentioned the engine had sludge inside. There is a possibility the oil rings are stuck on the Pistons. I would be pulling spark plugs and checking for oil contamination. Another post mentioned a compression test. One problem with that is the compression rings can test fine, but the oil control rings could be stuck or worn. Pull the plugs and inspect for oil would be my next step.

Were the valve stem seal rings ever checked to see if they were broken?



Notice the different colors for ex and int valves.....

Is the smoke coming from the tailpipe or from under the hood?

from the tailpipe.

I changed the plugs soon after I bought the car....they showed no signs of oil fouling.

How much oil are you actually using say every 1,000 miles?

if you haven,t done it , you might consider changing the pcv valve ! if it gets clogged it can cause oil to enter the air filter and suck into the throttle body ! i have a 97 lesabre and iam getting ready to change the pcv valve on mine !

I just put in a new one from Auto Zone.....still smoking.

Did you put the O RING around the PVC VALVE when you replaced it ?
yes I am sure this is only engine alive that takes a O RING around the base
the PVC VALVE

if it smokes at first start up then it,* bad valve seals !