Here's an intereting report on Mobile-1 and oil changes in general. Complete with graphs and science data. Plus regular words for us regular folk.

Mobil 1 Test Results

 

They added 6 and 1/2 quarts during the test. How can they say the oil lasted 18,000 miles?

 

porsche, whose motors are certainly not cheap, recommends changing mobil 1 every 15k miles or once a year - whichever comes first. bmw has a computer dictated service interval and it's usually in the 10k range. both these car manufactures have motors costing several times that of the F150 which they have to warranty. you'd think their service interval recommendations for mobil 1 are probably conservative as self interest would dictate.

 

Yea, sure why not. My friends BMX X5 had its first oil change at 11,000 miles, thats when the computer on the dash told him to change it....