Has anyone tried synthetic oil in their FEH? I just bought a 2006 and I am wondering if I could switch to synthetic (I have used Castrol synthetic in all my other vehicles).

I do not expect to change it until 3,000 miles, but would like to know

I changed my oil this past weekend and did use Castrol Syntech. Obviously, it's too early to post any results. I forgot to get samples of the oil for testing, but I definitely will the next time. I had just over 2700 miles on it and I plan on sticking to the 10,000 mile interval from here on out.

My 4WD
Wife's 4WD

Had dealer put my Mobil 1 5w20 in at 10K miles.

They put all five quarts in, overfilling the sump :-(

No apparent change in economy one way or the other. Whatever oil you choose, make sure it meets the Ford spec... (something)-930A to ensure no arguments over warranty if anything goes wrong down the line. It'll be on the back of the bottle.

I will avoid the "Castrol Syntec isn't really Synthetic" flamewar if at all possible...

The syntec does meet the 930A spec as well so no warranty worries there.

My 4WD
Wife's 4WD