In the first case, the Magnusson-Moss Act expressly forbids such stipulations. In Europe, motorists routinely pay premium prices for synthetic motor oils for the single benefit of improved fuel economy. Heavy-duty diesel transmission and differential OEMs warrant their products over a longer life with synthetics than with conventional lubes and engine OEMs are moving in the same direction. Top quality products always cost more than lesser quality products do. But you get what you pay for.
Every attention is given to producing the finest motor oil in the world.
With that finest motor oil money can buy, you, the consumer, get the best engine protection and motor vehicle performance, bar none. Many conventional oil companies just started offering synthetic and synthetic-blend oils within the past six years and did so to cash in on a lucrative market. It'll stop when the engine is clean. No need to wait for rings to seat or parts to wear in. They'll do that on their own.