I have a Toyota 2004 Sienna minivan and have faithfully replaced
my oil with Toyota recommended oil and averaged 21.5 MPG.
Now I am getting 24.5 MPG! That is a 14 percent increase in fuel economy!!!
I thought it was a fluke, so I tracked my usage again.
Same numbers!
With 150,000 miles on my minivan and averaging $3.25 a gallon,

I could have saved $2,776 in gas!

Also I change my oil every 7,000 miles now
instead of 3,000 so it is a break even on the cost of the oil!