We've seen higher tar content, both due to fuel quality and higher engine temps. Within the last 2 years we have also seen higher sulfur content. Sulfur content is required by CARB to be 80ppm or lower and we have seen test results as high as 213ppm. But of course the supplier claimed his fuel was pure. I am not a fan of bigger government, but the only way to cure this is that the LPG Industry needs to be regulated just like the gasoline industry was many many years ago.