I have a 65 Custom with a 352 big block. The motor is using oil at an alarming rate after the engine gets warmed up. The valve seals were just replaced. And a small intake manifold leak was repaired. The thing is, the motor runs perfect. No blue smoke. The car has only 42K actual miles on it. My mechanic really doesn't want to tear it down cause it runs so nice. I drove it around 40 miles today, and it was down at least 2 quarts. Any suggestions?