How good is the Shell Rotella T synthetic 5W-40 for both a high-performance gasoline engine and diesel engines?

Seems to be similar to Delvac 1, and maybe a little cheaper. The Salinas, Calif., WalMart had it 1-gallon jugs for $18.

I rubbed some between two fingers and compared to Mobil 1 15W-50 (between two finger on the other hand) it felt slicker, even after I wiped my hands.

:-) neil
1988 360TE AMG
1993 500E