Here's the thing. The purpose of oil today isn't just to lubricate parts, but also to trap contaiminants and keep them in suspension until the oil is removed. Filtering oil is essential for solid contaminants, however disolved contaminents remain in suspension in the oil till it is removed. Just about any oil, dino or synthetic, will do that job for you. However, synthetic is formulated to be more consistant on teh molecular level which is where most lubricants do their actual work. Synthetics also usually have a higher proportion of detergents in them and those detergents are the substances that are keeping contaminants and soot in suspension and preventing them from sludging up.

It has been said:
Hybrid drivers come in 3 flavors, greenie, techie and cheapie. Pick any 2.
2005 Prius, Melinium Silver over gray, package 5 (AI)