Ford Repair: 5w20 vs 5w30, mild weather, 20w50

Question
My original ford dealer (where I normally get my oil changes) merged with a new ford dealer several miles down the highway. So yesterday, I brought my 07 Sport Trac 4.0L V6 in for an oil change, and noticed after I looked over the receipt when I got home, that they filled it with 5w20 instead of 5w30. (which is what the manual calls for)

I immediately called the dealer back, but the Service Manager insists 5w20 is perfectly fine in my 4.0L V6. I went ahead and did some googling but can't seem to find a straight answer. Some people state 5w20 should not be run in the 4.0L, and others say it's fine.

I live in Houston, TX. We had our first freeze last night, but normally temperatures are mild.

I would really like to hear your opinion on this matter.

Thank you.

Sincerely,

 Richard de Vries

Answer
Richard-

  Honestly, I think the 5w20 will be fine.  Houston has such mild weather normally (at least it did when I lived there) that I don't see the change making any real difference.  And generally as long as you get close to what the manual recommends you'll be fine.  Just don't stick any 20w50 in there and you should be good to go.  Hope this helps.

Steve