[UFO]

Correct me if I read that wrong, I have not read it in detail, but this study is about using unheated oil in diesel engines. If you heat your oil and fuel only in a warm engine you will not have long term issues with the following caveats:

Water cooled, indirect injection only.
Change engine oil frequently.
Purge the vegetable before shutting the engine off.

That severely limits your engine choice, but there are thousands of successful VO conversions, some of them even in direct injection engines. But it eliminates all modern engines.

I have not heard of any effective mitigation once VO polymerization sets in though. I don't know if water injection prevents it either.