I've used regular motor oil all my life (mostly Phillips Trop-Artic or Valvoline) with no problems. I live in the midwest and it gets well below zero at times, as well as very hot in summer. I'm mostly attratcted to synthetic (Mobil 1, etc.) because of the low temperature flow characteristics for cold winter starts. Does it afford superior protection at high temps as well?
If so, then why doesn't everyone use it??
I know it's more expensive but that should be negated by the fact it can be used much longer before needing changed. Are there any issues with switching to it after an engine has 130K? I just bought a '94 Caravan 3.3 which has been serviced at the dealership since new with conventional oil.