Guys, I meticulously track my mileage ... to the point where I would notice tenths of an increase or decrease. If you want to 'test' the effect of products on your mileage, you MUST do this. Saying "I get between 18 - 22mpg" is completely useless as back up. Often any increases and decreases will be slight and meticulous data is required to quantify them.
I ask anyone that claims products increase or decrease fuel economy, please post at least 5 data points before and 5 data points after the change. Take an average and compare. If you are honest, and drove the same way, the same mix of city and highway, you'll have a legitimate claim.
This stuff thickens oil ... period. That thicker oil may provide better protection ... but the industry has been going to thinner lubes like 5W-20 ... which have been performing really well according to UOAs.
The seat of the pants dyno is saying these engines run better with this stuff? Smoother? Well of course a thicker oil will dampen mechanical noises coming from the engine. This does not mean it is protecting better ... just masking the sound of a worn or out-of-adjustment engine.
The idea that a thicker oil (with no known friction modifiers) with greater hydrodynamic drag will
increase fuel economy flies in the face of simple physics. Where is the savings coming from? What principle of physics is at play here?
But if you can provide good data to back it up, I'm willing to look, listen and learn.