Regarding Additives in Oil
Duralube, I believe is PTFE particles in suspension. This is the same story as Slick 50. The only one that I know of has some merit is called Prolong. It is an additive that is not suspended and it is not PTFE. It is a homogenous mixture of friction reducing additives that are not micro particles, so the additive has no chance in getting filtered out.
I still recommend that change the oil every 3 months or 3000 miles and your engine wil be in great shape.
See in engine oil what wears out with time is generally the additives that are used.
Synthetic is better yet except for the cost. I would suggest Synthetic only if you change the oil say every 7000 miles.
I simply use 20W-50 weight oil in summer and 10W-40 in winter.
I use it in my Porsche, BMW and Mercedes.
Another better engine oil which is Synthetic is Amsoil which is almost loaded with anti friction additives but the oil is expensive, they were the first who developed synthetic oil. this oil is used generally in race cars or heavy duty daily use where ultimate protection is required.