The EPA database on heavy duty engine emissions is publicly available at http://www.epa.gov/oms/certdata.htm under large on-highway engine, 2007-2008 model year.  The PX-6 is certified as Cummins engine family 7CEXH0408BAC.  You should be able to find the gasoline and natural gas engines emissions data in the same file. 

As long as users understand the risks of using biodiesel, take the proper precautions, and have a good quality source, the risks are low.  If you have been using B10 successfully over a period of time in your International engines, I wouldn’t discourage you from trialing B20.  Many fleets are running B20 with very few issues.

That said, International cannot expressly endorse blends higher than B5, because there are insufficient specifications for the blended fuel.  Use does not void the warranty per se, but if use of biodiesel is shown to be the cause of a failure, than that failure is the responsibility of the user or fuel supplier.  The same would be true in the case of failures caused by any fuel or additive.

Poor or inconsistent quality tends to be the number one problem with biodiesel.  We recommend that anyone wanting to use biodiesel seek out a source of supply that has BQ9000 certification from the biodiesel board.  The biodiesel board website, www.biodiesel.org, is an excellent source of information on how to successfully use biodiesel in your fleet.

There is a minimum lubricity required by the new diesel fuel standard.  All on-road diesel fuel is required to meet this standard, so there is no need for individuals or fleets to add lubricity improvers to their fuel.  Removal of sulfur does reduce lubricity, but any necessary additives will already have been added by the fuel refiner or distributor.