Actually they are just producing it for purposes of licking the money out of the pockets of very vain people. Additivs are totally useless, and I agree with theveed when he said regular change oil is much better coz it is not just better it is more practical.

Synthetic oils have better quality (it is true, usually it is more refined and heat resistant than ordinary oil) thus its utilization can be extended on a longer period. But in my case, I'd still prefer the frequent change oil using regular or semi synthetic oil. Coz aside from paying less, inspecting the drained used oil will give you an idea of ur engine condition plus you need to change your oil filter in a regular basis to ensure smooth oil flow. It might be that your synthetic oil is still good after so many kilometers and months because its more expensive and it was designed to behave that way. But you do not know that your oil filter may be clogged after after a prolonged period of utilization which by the way is a worst thing. In this condition I'd say that practicality is way better than vanity. Except when in cases wherein you are after for the performance enhancements offered by synthetic and speciallized oils when you are into drag racing or off-roading competition. But with ordinary driving condition, you are better off with ordinary oils.