number of reasons not to try it..... Ford has been running 5w20 since 2001 , is this a 2001 or newer? Also by ford's own data the gas mileage increase going from 5w30 to 5w20 is about 1/2 of 1%. And with 200k miles and some wear based on oil consumption, I'd just stick with 5w30 to make sure that there's a thick enough film of oil there.
Originally Posted by ryan roopnarine