Originally Posted by incubus625
You gotta look at it from a cost stand point to. Intake and exhaust may get you maybe 1 mpg more. but the cost for that extra mpg is rediculous. What you could do is replace your tires with Lrr tires when the time comes, switch to 0w-20 motor oil, etc. I dont have the new focus but I have a fiesta. So I do plan on switching to better tires when the time comes.
Is it wise to switch to a lighter oil? Wouldn't ford suggest it if it was safe to run it? The new mazda 3's run it so i am sure if ford thought it was safe they'd run it too. The new mazda3's run the engine on high idle for a bit when you first start it, maybe it has to do with the grade of oil.