You mention the Chevron 5w-40 synthetic and the shell rotellaT Synthetic 5w-40.
These are both groupIII nonsynthetic basestock oils being marketed as full synthetic. First you badmouth castrol and are on the fencepost about mobil then talk good about two more companies who are clearly in the same boat as castrol? hrmmmmm, ok.
2003 Jetta Wagon TDI 145,000MI
1999.5 Jetta TDI 287,000MI
2001 Suzuki SV650S 26,000MI
2008 Yamaha Vino 125 11,000MI