And out of curiosity, how would going to WVO destroy an engine? Everything I have seen says as long as the rubber does not come into contact with the oil as it degrades over time when it does, it will run just fine.
The two main issues seem to be coking of the engine, and the effects of running high viscosity oil through the injection pump. The cost of an engine rebuild is in the $5000 range and the replacement injection pump costs about $1600 new or $800 rebuilt, so most of these engines end up being junked if someone messes them up.
Some folks claim they can successfully run this junk by filtering, de-watering, and preheating the fuel within the car (assuming they have a reliable source of oil without significant animal fats, salts, or sugars), we’ll see how they do over the long term. Others claim they don’t have to heat it and can reduce the viscosity buy blending it with diesel or gasoline. Some folks process their own bio-diesel from WVO, which is significantly more complex. Make sure you really understand the differences between WVO, homemade bio-diesel, and and commercial bio-diesel; they are three very different things. Your comment about rubber makes me think you are referring to bio-diesel, not WVO.
IMHO, you might get away with this (for some amount of time) if you know exactly what you are doing, but doing it “correctly” seems like much more time, trouble, expense than it’s worth.