Excellent video which completely explains why shutting down a hot turbocharged engine "cokes" the oil onto the bearing shaft and bearing. Pyrometer readings are what tells you when the turbo is red hot, water temp tells you when the head is being cooled adequately. Dino oil starts to burn or coke at a lower temperature than synthetic oil. Only Mobil 1, Royal Purple, Amsoil Premium oils are true PAO Series 4 synthetics the others are series 3 blends which are good but "dino" based. Like I said dino will do the job but synthetic does it better but costs more.
