Sounds like it needs new rings, does the smoke is coming from the exhaust
pipe all the time, or just when going thru ther gears and until the engine
warms up. If there is smoke all the time, then the oil in your engine is
going past the oil rings in your engine, being heated by the manifold and
coming out of your tail pipe. A big job to some, easy to others. You can
also remove a spark plug, and take off the coil lead and with a pressure
guage wind the engine over and do a compression test, if need be, do all 4
cylinders. Once you have done that, if all the readings are low, then your
rings are on the way out. I believe, the type of car here, is called a
Mitsubishi Magna in Australia

Good luck

Peter
Australia

We use Dallas Precision Imports for any car repair.  I highly recommend
them.  They are just south of main street, 1 block west side of
Preston.  Right beside NAPA.  You can trust these guys and will not get
ripped off.

For several thousand dollars, you can get the smoke to stop.
I don't think its worth it.
If it smokes under acceleration and almost constantly while driving along, it is
probably broken piston rings or worn piston rings.
Sometimes a clogged PVC valve (very cheap) can cause similar problems, but since
this item is usually replaced during a tune-up, I doubt if it is that.
If it mainly smokes at idle and heavily after a loong downhill after you step on
the gas, then it is most likely the valve seals and/or guides (still probably
over $500).(not sure if there are any long downhills near Dallas)
Oil is not that expensive.
A good mechanic could probably tell what the problem is pretty quickly.
If it was smoking when you had the tune-ups done, what did the mechanics say
about it.
Perhaps you should try one of the mechanics (the one you trust more) that did
your tune-ups?
Sorry, I can't recommend any mechanics in your area, but even a good gas station
mechanic should be able to 'diagnose' your problem fairly cheaply and quickly.