Custom89 - if you're showing blue smoke and fouling plugs then your rings aren't sealing like they should. Not to say it won't run on for quite some time, but if you were to run a leak down compression check on the cylinders, my guess is it would show that you're losing a pretty good amount of compression. Other culprits are valve seals/guides - although, that usually shows up with a big puff at start up, or when decelerating. If it truly was that way when new, someone missed a wonderful opportunity to have a warranty repair. A quart every 500 miles is excessive by just about any standard. You'd likely be amazed at how much better it ran with solid seal on the cylinder.
As for low-friction piston rings - cars manufactured today set standards for quality assembly, consistent tolerances and low friction design that's far ahead of anything 15 years ago. And the vast majority don't use any appreciable oil between changes. Low friction rings don't necessarily mean that an engine will use oil. I suspect the variable level of oil use has more to do with a relatively lax quality/assembly protocol by Ford originally. If you measure a bunch of engines out there, the dimensions are all over the board - quality wasn't really job 1. But, the quality's good enough and the engine/components are just plain simple and tough enough that they hold up real good over the long haul.
