Might not be an "upgrade"
19's are likely lighter.
if you want the looks of 20" wheels just buy them. The difference in ride quality or performance will not be huge. It's only an inch.
Because the owners manual covers their ass. Anyone who stores cars doesn't start them up every other week.
They just don't want people having to bug the dealer when they park it for a month.
You're babbling around the question I asked.
The cold viscosity of a 5W30 and 5W40 are both going be in the same range as they are both 5W.
The '40' doesn't come into play until the engine oil gets to operating temp.
So why are you saying:
And what does this mean?
Which would be? Depending...
A cold start every two weeks is pointless. That's the #1 cause of engine wear. Plus you then want to get it up to operating temperature which is going to take a while if it's cold where you when it's just sitting.
Just leave the damn thing off until you're going to drive it in spring.
Look at Ford page for the RTR EcoBoost:
Performance & Capability
Mustang Dark Horse Adjustable Strut Alignment Bracket 
Mustang Dark Horse Handling Pack Front & Rear Stabilizer Bars
Mustang Dark Horse Rear Subframe with Stiffer Rate Bushings
Mustang GT Steering Rack Angle with 72.5...
Just tossing around some numbers, found this interesting...
this full street car made good use of the intercooled centrifugal offered by a hearty ProCharger F-1A94 head unit, pumping out more than 24 pounds of boost.
ported stock intake and heads ported by AFS.
8.95 at 155.50 mph
Now...
On the other hand, with E10 the ethanol will absorb the water so you don't get straight water collecting in the tank
You can also just use a screwdriver or sothing to push the other tab in