The difference of the bio fuel raw material, processing, and additives make the difference in messing up lines, pumps, Ip, and injectors.
Not all the fuel companies like running bio in their product. The 2 largest fuel suppliers in Nv loose profit to it, but it is law, so they do it (at least when I worked for them a few years back). One outfit made some wicked junk bio from peanut oil, followed up by high end stuff from soy. same process, way different results.
Methanol / ethanol use in any fuel is to burn cleaner in the name of less pollutants, see oxygenated fuel research. The hilarious part is that pure alcoholic rides like my ol '69 Camaro at one point put out amazingly low smog testable emissions- but try to breathe that exhaust and you'll be dead in a year.
Methane (C1), ethane (C2), propane (C3) and butane (C4) are far better choices for emissions and health of people/ animals but the availability makes it harder to deal with. That is until the demand goes high enough that the refineries decide to crack the hydrocarbon chain with longer run times. That of coarse adds cost to the fuel but is a serious long term possibilities.
As far as the #2 being better than bio- well that is a simple decision of the mfr of the bio. Better product simply costs more to buy. Everyone says they want the best fuel, but then gets upset at high fuel prices. At the company I have been working for doing the plastic to fuel stuff, We created a diesel fuel that has absolutely amazing lubricating properties with almost no recordable sulfur so it burns way cleaner than normal fuels; basically all that and a bag of chips. The problem is by time it would get to market in it's pure form $8 a gallon would not sell. Although you get the bag of chips, you are paying for it. So... the refinery's want to buy it as a sweet crude non distilled and mix with their oil part way in the distillation process. It will make their product better, but cost a little more to the end customer.
It isn't just bio fuels btw. Refineries get their crude from different sources and that has massive impacts on the fuel they produce. Have any of you wondered why trucks in 1 part of the country can get better fuel economy that the same truck at same altitude and driving conditions. There is a range of btu's, flashpoint, reed level, lubricity, etc. that the fuel can fall into. Those ranges have a decent impact on the life of the parts and of coarse efficiency.
Bugs are always associated with bio fuel, but bugs are in conventional fuels (yes gasoline, kerosene,jp4&8,etc) as well. They just are larger in bio, and when it is not treated properly can propagate at 2-3 times the rate in high heat climates. Want to run any fuel without the fear? a dry centrifuge in the truck gets it all, no bugs below 1 micron. DO NOT USE A REGLUR CENTRIFUGE!- EL-BOOM-O! under right or wrong circumstances.
If you really want a rating on the fuel, you can get it from them. You just need a month in hydrocarbon chemistry lessons to have it help yo understand the differences. I've got some time in over the years dealing with it on off, and still have to go "what was that again?".
