That phonecall will be a long way off...
I would follow the owner's manual advice for your area. You're in Florida - the weather is hot - go with the 20W50.
I live in Canada and I currently use Castrol Syntec 5W-50. The summer here will get hot (+35C) and occassionally it will also get cold overnight (down to zero) in the summer. So I like the wide range of the Syntec.
2007 E550 4Matic - 61,000 Km - Iridium Silver, black leather, Sport package, Premium 2 package
2007 GL450 4Matic - 62,000 Km - Obsidian Black Metallic, black leather, all options
1998 E430 - sold
1989 300E - 333,000 Km - sold
1977 280E - sold
1971 250 - retired
"And a frign hat. They gave me a hat at the annual benefits meeting. I said. how does this benefit me. I dont have anything from the company.. So they gave me a hat." - TheDon