I have 2005 V10 that has 78K miles on it. I have always and only used Motorcraft 5W20 semi synthetic oil and FL820s filters. I just changed my oil and didn't realize until 6qts were in that I purchased Motocraft 5W30 semi synthetic. The owners manual doesn't recommend anything other than 5W20. Will I have any problems?

 

If you were south of latitude 40, I would say no issues or risks whatsoever.

But you profile says upstate NY. Brrr. Qualifier time....
If you park your truck outside with no block heater, you may want to try to avoid or at least minimize start ups on sub 0 degree days. Other than that, good to go!

Things in your favor:
Ford orignally spec'd 5W30 for V10's, and it does not appear there were any design/bearing clearance changes when the spec changed.
Your engine s/b broken in by now and not super tight.
Semi-synth will flow somewhat better than non-synth at low temps.

 

Thanks for the reply; sort of what I thought about the 5W30 BTW. I am in Florida and headed for the Texas coast for the rest of the winter! I lived in upstate NY (Rochester) for 60 yrs and I don't need that winter scene anymore!!

 

Oh, you'll be dandy then!
Some even prefer to run 5W30 or 10W30 during hot summers.

I will likely switch to full synthetic 10W30 after the new engine has 50K miles as it almost never gets below freezing where I am.