1990 tercel started smoking and using oil

could be piston rings are weak.how many miles on car?

After a proper diagnostics we can determin if the compression in your engine is still good or not. You may simply have seal leaks and a head job could fix the problem. Or if the compression is low you may need a new engine. When you are driving on the highway, the parts in your engine move faster and the oil tends not to leak out into combustion chamber and burning in exhaust. You are at risk to perminately damaging your catalytic converter at this point.