Sta-Bil for your fuel, package tells you how much to add.
On the topic of starting or not starting a car in winter. This was discussed @ length on the SVTP site, one of the members posted this:
From the 2013 Mustang Owners Guide V3 - Page 258
If you plan on storing your vehicle for an extended period of time (30 days or more), read the following maintenance recommendations to make sure your vehicle stays in good operating condition.
All motor vehicles and their components were engineered and tested for reliable, regular driving. Long term storage under various conditions may lead to component degradation or failure unless specific precautions are taken to preserve the components.
• Store all vehicles in a dry, ventilated place.
• Protect from sunlight, if possible.
• If vehicles are stored outside, they require regular maintenance to protect against rust and damage.
• Wash vehicle thoroughly to remove dirt, grease, oil, tar or mud from exterior surfaces, rear-wheel housing and underside of front fenders.
• Periodically wash vehicles stored in exposed locations.
• Touch-up raw or primed metal to prevent rust.
• Cover chrome and stainless steel parts with a thick coat of auto wax to prevent discoloration. Re-wax as necessary when the vehicle is washed.
• Lubricate all hood, door and trunk lid hinges, and latches with a light grade oil.
• Cover interior trim to prevent fading.
• Keep all rubber parts free from oil and solvents.
• The engine oil and filter should be changed prior to storage, as used engine oil contains contaminates that may cause engine damage.
• Start the engine every 15 days. Run at fast idle until it reaches normal operating temperature.
• With your foot on the brake, shift through all the gears while the engine is running.
You can make your own decision, it is after all, your car !!