The Oil leaks are the only way you know for sure you have oil in it. In all seriousness, my engine does not leak Oil. I used Yamabond #4 on the oil pan and soaked the cork valve cover gasket for days in water before mounting it. That's the place where oil can seep. Keep on top of that, and there's no problem. Since you should check the valves every 1500 miles, checking the gasket is part of the maintenance. Switching the carburetor to a 40Mmm Weber Sidedraft and putting a modern fuel pump is what made the car reliable, (and blueprint the engine, shot peening the rods, forged pistons, 10 degree duration cam) the little bits and pieces.