Smoke coming out of oil dip

If you're referring to the oil dipstick tube, smoke is not uncommon but there should be a better seal on it to prevent that. The smoke can be caused by "blowby". That is exhaust gas that sneaks past worn piston rings and gets into the oil. It can also be raw gas, moisture, and other contaminants in the oil that is vaporizing and burning off. This is more common if you do a lot of short-trip driving.

Those vapors are supposed to get sucked out by the PCV system. That's the positive crankcase ventilation system which includes an inexpensive valve that should be replaced periodically. If you see that smoke while the engine is running, start with a new PCV valve. If the engine is running okay, there is no need to rebuild it.

I think I would look at your comment of "no performance issue" and live with it for now. If you do a lot of short-trip driving, there will be blowby that condenses in the oil and won't burn off right away. If it vaporizes and burns off later, that could make more smoke than normal. There could be an additive in the oil that is vaporizing. Regardless of the cause, if it's not causing a problem and the engine is running normally, I'd leave it alone.

To tell if it is due to worn piston rings, your mechanic can do a "cylinder leakage" test. A compression test will identify any cylinders with low compression. A cylinder leakage test will tell you why it's low. There's four possible causes and four places to look. The causes are a leaking intake valve, a leaking exhaust valve, a leaking cylinder head gasket, and worn piston rings. The leakage test involves blowing compressed air into each cylinder, one at a time, and listening for where it comes out. If the piston rings are worn, you'll hear the air hissing at the oil cap or dipstick tube.

Sorry for ignoring you for so long. My e-mail service went through some changes, ... Again, and I didn't get a lot of automated messages.