Re: engine smoke
If the oil is only on start-up, that points to valve stem seals rather than worn valve guides. Here's the reason--when valve stem seals age, they crack. Any oil that's left on the top of the valve at shutdown flows through those cracks and down the valve guides. Sure, the guides might be worn a little, but if the valve stem seals weren't cracked, they would do what they're designed to do--seal the valve stem. Now, having said all that, you may still have a case of bad valve guides. You're getting blue smoke on start up because the cat converter hasn't warmed up enough to burn off that oil. If the valve guides are worn to the point where engine vacuum is sucking oil down the guide, that might not show up on a warm because the converter is hot enough to burn it off. On the flip side, all that extra oil would cause your converter to run hotter than usual. And it would result in even lower post cat O2 sensor readings because the extra burn off would use up all the available oxygen in the exhaust stream. Bottom line, only a compression test can tell you if you have worn guides. You'd have to do the test at least twice to see if the valves are wiggling in their guides. Valve stem seals are cheap and the job isn't too hard.