I've used soybean oil from World Energy in my
L4150 and later my
L5450 (1995) for a few years - mostly in the warm months - I found it clouds at a little higher temp than they advertised.
It's power and fuel usage is very nearly the same as petro-diesel- maybe a few percent less but not really noticeable. The downside is cost. I buy a 55-gallon drum but it still averages almost $5 per gallon, delivered. Being an environmentalist is nice - but it's costly.
The great part is when I'm mowing, it smells like the fry tents at the county fair instead of an airport or bus station.
I've never dared to use the used cooking oil products - too worried about water content.
I posted about this a few years back - mostly got pounded for spending so much on fuel. Change can be slow. /forums/images/graemlins/smirk.gif
Biodiesel is not catching on at a quick pace - the infrastructure (pumps, tanks, dealers) hasn't reached into most areas yet - but one of these days the environmental movement will "discover" this option again and who knows, maybe it will fly. Like any new fuel, it will need a big push from the Feds - but that doesn't seem likely any time soon.
Take care,
Dick B