Just for arguments sake. If running unheated veg oil cokes the rings somewhat I do not see it as the end of the engine. Or having to tear the engine down.
That vegatable coked residue if there seems to be correctable by a good soaking with marvel mystery oil. It is certainly not totally certain but after a soak in general the compression numbers rise substantially usually. The marvel mystery oil seems to slowly break down the carbonized vegatable oil that has accumulated in the ring grooves that made the rings sticky. . Or perhaps there is not enough heat to actually really carbonise it so it just has become a very sticky type glue instead.
I believe a lady also sat an injector in a dish of marvel oil and saw the carbon dissolving off the nozzle end over sevral days so something is happening with the snake oil.
If nothing else it is worth a try in my opinion. A cheap and manageble approach with really nothing to loose even if it did not work. Although once you have lost so much sealing function and the vegatable oil is showing up in the base oil in quantity it is beyond my knowledge. Although I would not think the engine runnable at all with that much sealing ability gone. Yet that is exactly what some threads may indicate has happened.