THe ol' 199 I6 in my rambler feels like it runs good, isn't noisy and there isn't any blowby but everytime I check the oil shes down a quart. I just got it a few weeks ago so I don't know the history..but I've been running it on the highway lately at about 65-70 mph. could it be the guides or valve seals etc? thanks
If it's 40+ years old chances are it's eating it, but what I would do is go to a car wash (the wand type), clean the whole engine off (bag the distrib first if it's points) then next time you park it put down clean newspaper with rocks to hold it down. A day or two later spend some quality time on your back under the car in a zen-like state and look for leaks.
In order: valve cover, oil pan, rear & front seals, timing cover, head:block, then everything else. After 40 years engines make stuff up you'll never think of.
If valve cover or oil pan leaks, you can tighten the bolts but JUST A TINY BIT, it you wrench down on the thin metal it simply bows between the bolts and leaks worse. "Two fingers on a nut driver" amount of torque. Keep in mind it's a "seep", not a pressure-driven leak like a hose. You could just about press the cover on with your hands to stop the leak. It doesn't require tight bolts to clamp it.
Valve cover bolts seem like they're designed to self-loosen. If gasket material is missing or falling out, get a new gasket and change it. Get the surfaces spotlessly oil-free, use silicone and glue the damn thing in place. Don't let much ooze into the valve area though.
Same goes for the oil pan, but a fairly huge deal to remove it of course.