I have seen the above posted here and other boards where the usual line is I have used xxx dino for all my cars and never had a problem and I can't see spending more money for synthetic. Or, I used synthetics and didn't notice any difference in wear for my 3k change interval so I am sticking to dino. Yet I wonder what it is that is expected. I have noticed many people who run a flush or autoRx and immediately notice how much their gas mileage picks up and how much quieter and smoother their car runs afterwards. These flushes or cleaners do not increase fuel economy, they merely return the car back to its optimum state. It was the dino oil that caused the lower fuel economy in the first place. This point is lost on most. In todays world of gas prices approaching $2 a gallon, this lost efficiency is definitely a cost associated with using dino. I have not seen anyone who has used a PAO synthetic use autoRx or a flush and come away saying they had an increase in fuel economy. I have seen many say they switched to synthetic and did notice an increase in fuel economy. Extended drains make the cost between dino and PAOs negligible. Inceased fuel economy puts the synthetics in the lead. The extra protection at temperature extemes are a bonus in the cost comparison. The only benefit that I ever see people who use dino to justify using dino is that its price is less. Yes, but what are the costs associated with the lower price? I run Amsoil because I can't justify spending more money over the long term using cheap dino. That and I like my free time.