While looking at the Lubrizol spiderweb diagrams for the n-th time, I noticed that the "aftertreatment compatibility" gap between 229.5 and 229.51 specs has shrunk in the most recent versions. Below are the diagrams for 2009 as well as 2012 versions of these specs. Somewhat strange actually that the latest 229.5 spec has improved in aftertreatment compatibility even though it's still basically a full SAPS spec with the same limits on sulfated ash, phosphorus, etc. as back in 2009. So then, what has changed for 2012 that caused the 229.5 spec to become so much more emissions equipment friendly? Or are these Lubrizol diagrams just not reliable? 2009 version on left. 2012 version on right.