I read about a fix for leaks in a rod magazine several years ago and although I've never used it, it sounds like a viable operation. Rig a vacuum line to your
oil filler tube to pull a vacuum in the crankcase. This could be a vacuum adapter for your shop air or you could tap off the manifold of a running motor. I suppose you would have to run a fairly long line to get the motor noise of the running car away from your unrunning motor. Using a stethoscope, pick around the motor with the probe until you hear air rushing in. Put a dab of RTV there and the vacuum should suck it in to seal the hole. The guy who wrote this originally said that he completely sealed the engine using this method and had no more driveway stains. Hope this helps. Richard.