Q: I got a 2000 dodge ram pickup that ran out of oil i dont know when. It started makin a light knockin from the engine.

The sound you are hearing is likely related to the lack of sufficient oil in the motor, which may have also caused the motor to overheat and shut down. When this happens, a number of things may cause the motor to not run properly or not start. As the motor overheats, the internal components begin to expand causing things to eventually breakdown the oil heating it up faster and faster. As whatever limited oil is in the engine is pushed around, it becomes hotter and hotter. It becomes hotter because the oil isn’t allowed enough time to cool down before it is required to go back into the engine and do its job. Several reactions happen to the oil, to include oxidation, thermal degradation, and compressive heating. All of this breakdown creates the regular: tar; sludge; varnish; soot, etc, which begins to start being deposited on the internals of your engine, such as the rings, bearings, cylinder walls or anywhere else oil would normally flow. As these carbon substances continue to deposit, any part which comes in contact with them gets wear on them as carbon can become quite hard and/or sticky under the right circumstances. This starts creating more friction on these parts as a result of the oil has breaking down and now heating (due to more friction), creating deposits, and causing the engine to heat up very quickly. Eventually, this will increase to a point when something such as a piston rod will break resulting in catastrophic damage to the motor beyond repair. I would recommend having an expert from YourMechanic come to your location to take a look at your vehicle to properly diagnose.