i just switch to synthetic like last week and notice i'm getting less mileage then i did when i use regular oil....i'm going to drive more to see if this is true or not...

 

You can't run an accurate mileage comparison on just one tank unless it is done under very controlled conditions...there are way too many variables to draw a conclusion. I have logged every drop of gas that has ever been put in my car and I am consistently getting 28/29 mpg with AMSOIL 0w-30.

 

As he said.

I've noticed no change at all in either vehicle.

 

Improved fuel economy is a secondary benefit of synthetics. If you are expecting drastically improved fuel economy by switching to synthetics, you will be disappointed. Based on my experience, most folks will experience an improvement from 2% to 5%...some claim more and some may not experience any improvement at all. If you're currently getting 25 mpg, a 2% improvement will amount to a half of a mile per gallon increase....very difficult to measure on one tank in an uncontrolled environment, but an increase just the same. Based on the amount of miles I drive per year, even a 2% increase will save me about $85...more than enough to pay for the oil...5% (1.25 mpg increase..not huge, but I'll take it) would save me over $200/yr in savings at today's gas prices.

 

After I switched to Mobil 1, mine went from 16.5-18 mpg to 19-20 mpg. The improvement was noticeable from the first tank.