2003 Ford Explorer 4x4 4.6L V8 oil change?

I have a 2003 Ford Explorer 4x4 with the 4.6L V8 with about 137000 miles and it's due for an oil change and its the first since I have owned it but I do not know what the previous owner used. The manual tells me to use 5w20 but I have been told its probably better to use 10w40 because of the mileage but I don't know if this is true. Also full synthetic vs synthetic blend? Best brand?

TIA for responses!

Go with the manufacturers recommendations on 5w20, but choose a high mileage oil. Most oil companies make a high mileage oil. In all honesty, in a Ford with that many miles, other components will go before the engine does, just maintain oil changes and the engine will outlast other things on the suv.

Split the difference and go with 10W30. Forget the synthetics unless you live where it is very hot or very cold there a waste of money.

Making the assumption the previous owner/owners used what was recommended by Ford, the 5w20, and the vehicle has gone 137k why would you want to change? My take is don't argue with success. Generally speaking unless you drive where conditions are extreme the synthetics aren't going to make much difference except to lighten your wallet a bit more.