that engine holds 15 quarts not to add milage to the oil change, but to allow for low and high pressure oiling systems. it does add some milage to the oil, but not that much. fords spec for gas motors is 3,000/5,000 depending on driving conditions and 5000/7500 for diesels......i would NEVER go 5000 on a gas motor....and another thing to think about....you know ford wants you to wear that motor out as fast as possible without it seeming obvious.....i would stick to 4000 miles on diesels....as a rule of thumb. the tech that wrote 3000 is probably a young guy that is new to the business....but i even put them at 3k on diesels just as a reminder. you will never hurt a motor changing the oil on shorter intervals....but you can slowly kill it going a little longer than what seems "standard"..........Marc