What might cause an Oil Leak? What maintenance issues cause this possibly and what can prevent it?

Maintenance issues with oil leaks?


and also -


In general what can be done to keep an engine in tip top shape


specifically for Chevy ';Cavaliers'; or any cars?What might cause an Oil Leak? What maintenance issues cause this possibly and what can prevent it?
Age, heat, wear, chemical breakdown in oil causing an acidic reaction which eats away at seals and gaskets, clogged crankcase ventilation valve, too much oil, too little oil, no coolant or poor coolant circulation causing a rise in oil tempature and/or pressure, over-revving an engine, using wrong grade of oil or mixing oils, nuts and bolts loosening off due to the cycling of expansion and contraction during warm up and cool down, improper grade of bolts, improper torque sequencing of nuts and bolts, improper torque, using silicone where paper gaskets should be, warpage of an engine component; ie (head/s) and not allowing proper warm up before driving when the engine is cold (oil is thicker when it's cold so there is a much high pressure upon initial start up). I hope I've steered you in the right direction.