'72 350 Engine with a 700R4 and 3.73 gears,10,000 miles on a full stock rebuild. The engine appears to be losing oil when it runs a lot of highway miles. We went through 2.5 quarts in 1100 miles, which included four 130 mile trips. PVC valve seems good. Seems to have good compression and it starts and runs well, though the exhaust pipes look mildly black. I am concerned that the short trip driving in the first two years of the engine's life did not allow the rings to seat. Never had one burn oil like this. Any suggestions?