What would happen if you put motor oil in the gas-tank of a car in Internal Combustion type Engines?

To protect the fueling system from contaminants, there is a fuel filter that holds rust, humidity, paint chips, other particles. I am not sure how efficiently the fuel filter can prevent engine oil from seeping into the fuel system.

In all modern cars (MY 1986+) There are On-Board Diagnostics (OBD) designed to monitor and diagnose malfunctioning of fuel system and components including fuel injectors, fuel rail, evaporative emission system, oxygen sensors, fuel pump etc.

Now I am not an OBD expert. But I know that in case of contaminants (Engine Oil for example!), fuel pump won't be able to maintain prescribed Fuel Rail Pressure. Fuel Injectors would be clogged and won't be flowing appropriately. This will cause misfires in multiples cylinders...... All of which is detectable by the engine controller and the overall OBD system. The system will set a fault and depending on the severity of the situation, engine controller will prevent operation of the vehicle or just set the "Check Engine Light" on instrument cluster.

Yuchai brand engine is leader of China diesel engine .