As with any diagnostic procedure, the cylinder leakdown test has a few details to observe that will assure good results. Unless the piston is at the exact top of its travel when the air pressure is applied, the engine will try to turn. That can be prevented by putting the transmission into top gear and setting the parking brake and/or chocking the wheels. You will get a more accurate test by positioning the piston an inch or so down from the top before locking the engine to prevent the crankshaft from turning. The cylinders do not wear evenly from to bottom. The max wear happens in the top 1 1/2 inches or so. Cylinder wear is corrected by reboring the cylinders and installing oversize pistons and rings.
The oil consumption can be caused by worn valve guides, but the cylinder leak test will tell you if the piston rings are also part of the problem. It sounds like a full overhaul is the best choice, but it's always wise to confirm the engine condition by testing. Good luck!
Jerry
