Synthetic Oil Myth?

I've read a couple of articles saying that Synthetic Oil is better for oil change than the regular ones. Synthetic Oild definitely has lower viscosity than the mineral oil and therefore ditsributes heat within the engine better and helps maintains a cool temperature. The myth is that when you start using synthetic oil you have better gas mileage and car performance. With my experience it wasn't.

I switched to synthetic oil 6 months ago and been monitoring it on a regular basis. While I was still using mineral oil my gas mileage was between 17 to 18.9 mpg. Just yesterday my car had 20.13 mpg. So my car was more gas efficient. I had an extra 1.23 mpg and since my car can contain 23 gal (full tank)  I gained an extra 28.29 miles. I'm not sure why it took 6 months to finally get value out of this wonderful oil. Maybe my car was still in the process of adjusting to the new oil. But it worked for me. My car is an Infinit FX 35 V6 2004.

I'm gonna continue using Synthetic Oil till my car finally give up the ghost.