dssur
+1y
usually you can tell which you need (rings or seals) by this simple test:
If the engine is down on power and smokes, its rings.
If the engine runs fan freakin tastic, but smokes either at warmup or all the time, its the seals.
I had a smoker with good power that had an oil ring stuck in with carbon. I had one with bad valve seals I put a new head on and the added compression of the new head caused the rings to go bad.
Mazda sells something called "top engine cleaner" that you suck in a vacuum line with the engine running till it dies. Then you let it sit over night, and ingest the rest while revving the engine. Its like 5 bucks a can and does a pretty fair job on carbon. I've had luck pouring some kerosene down the spark plug holes and letting it seit overnight, then running (idling and just over idle) the engine GENTLY (the kerosene thins out the oil, you'll spin a bearing quick) for an hour or so. Then change the oil and filter, and repeat after about 1000 miles. Cleans up stuff inside like carbon pretty well.