The biobore (sp, sorry) has a reputation for killing it all and setting it free in big chunks that block your filters. That is not an issue if you are pulling the tank.

The Startron has enzymes that eat/break the stuff up into pieces small enough to get through the filters and be burnt in the engine. Great for regular treatment to get a tank clean and keep it clean. I used the Startron only, but I did not pull my tank.

-Jim

__________________
1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.