Does anyone have any info on Shell Rotella T Synthetic 5w40? Is this Group III or PAO based? I'm curious. In my F350 Diesel I use Mobil Delvac 1 5w40 in the winter and Mobil 1300 Super 15W40 for the rest of the year. I'm paying about $17.50 per gallon for the Delvac and $5.75 per gallon for the 1300 Super. I recently noticed Shell Rotella T Synthetic 5w40 in my local Wallyworld for $12.88 per gallon!!! That is about $3.20 per quart which is quite a bargain in my book. Comments on the Rotella T Synthetic 5w40 anyone? Thanks.