Since one of the things I read and hear about is waste oil (in particular veggie oil) contaminating the lubrication oil in the engine, is there anything that can be done about this? Or does it just require much more often oil changes? (I would assume something like those bypass filters meant to extend oil change intervals would be bad)

Has anyone figured out exactly WHAT gets deposited in the oil or whether anything can break it down/aftermarket additives?

Another thing i've heard (for mostly veggie oil vehicles) is unburnable things being deposited in and gunking up the combustion chamber/valves, etc... again has anyone identified exactly what it is that gets deposited, and whether there is any way to prevent it (water injection? i've heard of it acting like a "steam cleaner" on some other engines) or if already present get it out without tearing the engine apart?