autogas (lpg) and valve lubrication

Hello,

As fuel prices this morning reached almost 2$ per liter I'm considering to convert my Prii to autogas. As it is not typical vehicle I have done some investigation, not every company is ready to do such conversion.
Anyway I'm not sure about valve lubrication. In many places I have been told that any Japanese car when converted to LPG needs extra valve lubrication. On other hand I have heard from some technicians that it is "bull poo" it's mainly because they are interested in selling as much stuff as they can.
Maybe there are someone who can explain a bit more about stuff.
My concerns are about:
-) is extra lubrication needed or not?
-) if yes dose it "eat" oil?
if yes:
a) how much and what is cost expectation for it?
b) how about catalyst, as I know it is not acceptable at all to have oil on it.
c) burning oil is not environment friendly
-) how dose conversion impact life expectancy of engine?

If someone has already converted maybe it is possible to get some data about economy and costs.
Maybe there is something else to consider?

Thanks and Cheers!

 

Thank you for pointing to that thread, somehow didn't found it before, strange.

But anyway my question is not only about LPG so perhaps I can be justified :doh: