How to Leave a Car for 3 Months: The Essential Storage Guide

Clean the car, fill the tank (and add fuel stabilizer for gasoline), inflate tires slightly above spec, avoid using the parking brake, connect a smart battery maintainer (or disconnect the negative terminal), cover and secure the vehicle in a dry, safe spot, adjust insurance, and don’t start it unless someone can drive it 20–30 minutes. For EVs, leave it plugged in with a 50–60% charge limit if possible; if not, park it at 40–60%. When you return, check for leaks and pests, set tire pressures to the door-jamb spec, reconnect the battery, and drive gently to operating temperature.

What to Do Before You Park It

Preparing the car properly prevents battery failures, flat-spotted tires, gummed-up fuel, seized brakes, and pest damage. The following steps apply to most vehicles and note differences for gasoline, diesel, hybrids, and EVs.

Supplies You’ll Need

Gathering the right items up front makes storage safer and reactivation faster. Here are common supplies that help protect your vehicle over a three‑month pause.

• Smart battery maintainer/tender (AGM-compatible if applicable) and extension cord; or quality jump pack for return
• Fuel stabilizer for gasoline (e.g., a modern ethanol-compatible stabilizer)
• Wheel chocks (two or four), not bricks
• Tire pressure gauge and portable inflator
• Breathable, fitted car cover (outdoor-rated if outside); windshield sunshade
• Moisture absorbers/desiccant (e.g., DampRid) for interior; small spill-proof type
• Rodent deterrents (sealed peppermint pouches or traps placed around the car; avoid toxic mothballs)
• Quality wash/wax supplies and interior cleaner

Having these items on hand lets you complete storage prep in one session and reduces the chance of issues during the layup period.

Step-by-Step Prep for Gasoline or Diesel Cars

These steps address the systems most affected by sitting: fluids, fuel, tires, brakes, battery, and interior. Follow them in order for best results.

1. Wash and dry thoroughly; apply wax or sealant to paint. Clean the interior and remove all food or organic debris.
2. If an oil change is due soon, do it now; top off coolant and washer fluid. Three months isn’t long, but fresh oil minimizes acid/moisture issues.
3. Fuel: Add gasoline stabilizer to the tank, then fill to near full to reduce condensation; drive 10–15 minutes so treated fuel circulates through lines and injectors.
4. Diesel: Fill the tank to near full. In very humid climates, consider a biocide formulated for diesel to deter microbial growth; anti-gel is only for cold-weather operation, not storage.
5. Battery: Best option is a smart maintainer connected to the battery posts. If you can’t plug in, disconnect the negative terminal to prevent parasitic drain (you may lose radio presets/clock; check the owner’s manual for any vehicle-specific procedures).
6. Keyless systems: Store key fobs far from the vehicle or in a Faraday pouch so the car doesn’t “wake up” repeatedly and drain the battery.
7. Tires: Inflate to the door-jamb spec plus 3–5 psi to reduce flat-spotting. If you have ultra-high-performance tires or it’s very cold, tire cradles help. Avoid long-term storage on jack stands unless the manual endorses it; suspensions are designed to carry weight.
8. Parking brake: Do not set it for long storage; pads/shoes can seize. Use wheel chocks. Park automatics in Park; manuals in 1st gear or Reverse. If your car auto-sets an electronic parking brake, check the manual for how to disable that feature.
9. Location: A clean, dry garage is best. If outside, choose a flat surface away from trees/sprinklers. Use a breathable, fitted cover (never a plastic tarp) and secure it against wind.
10. Interior: Close all windows and vents. Place small, stable desiccant tubs on the floor (secure to prevent spills). Make sure carpets and mats are dry to avoid mold.
11. Pest control: Keep the area clean, avoid leaving pet food nearby, and place deterrent pouches or traps around (not inside) the cabin. A quick flashlight inspection around the engine bay before covering is wise.
12. Security and admin: Remove valuables, hide or remove the toll tag, consider a visible steering wheel lock, and note the odometer. If permitted where you live, switch to comprehensive-only or storage insurance and confirm registration/emissions timing won’t lapse.

Completing this checklist largely eliminates the most common storage failures—dead batteries, bad fuel, seized brakes, tire flat spots, and pest intrusion.

EV and Hybrid-Specific Setup

Electric and hybrid vehicles have different priorities: traction battery state-of-charge, 12V battery health, and background features that can drain energy. Set them up as follows.

1. EV state-of-charge: If you can leave it plugged in, set a charge limit to about 50–60% and let the car manage itself. If you must leave it unplugged, park it at 40–60% and enable any “sleep/energy-saving” mode.
2. Features to disable: Turn off Sentry Mode/always-on cameras, Cabin Overheat Protection (unless required for pet/safety—then expect higher drain), scheduled preconditioning, and power-hungry third-party apps. Close windows and frunk.
3. 12V battery: Many EVs still rely on a 12V battery that can discharge in storage. If possible, connect a 12V maintainer directly to the 12V battery. For hybrids (e.g., Toyota/Lexus), a maintainer is strongly recommended; the 12V battery is small.
4. Tires and brakes: Same tire guidance as ICE. Expect a film of rotor rust; it clears with gentle braking on your first drive.
5. Monitoring: If the car supports app checks, peek monthly to verify state-of-charge isn’t drifting unexpectedly. Avoid waking the car daily, which increases drain.

Following these EV/hybrid steps minimizes battery degradation and prevents an avoidable 12V failure—still the most common reason an EV won’t “wake up” after sitting.

During the 3 Months

Once stored, the best strategy is to leave the car undisturbed—except for quick visual checks or a caretaker visit. Avoid short, periodic starts that never reach full operating temperature.

• Do keep the battery maintainer connected and verify it’s powered after storms or outages.
• Do have a trusted person check monthly for cover fit, rodent activity, and leaks; if feasible, have them roll the car a few feet to change the tire contact patch.
• Don’t start the engine unless it will be driven 20–30 minutes to full operating temperature; short idling invites condensation and fuel dilution.
• For EVs, don’t enable energy-intensive features remotely. If unplugged, confirm SOC is within the safe range and not falling rapidly.
• Keep key fobs stored away from the car to prevent wake-ups.

Minimal disturbance preserves the work you did up front and avoids creating condensation or unintended battery drain.

Bringing the Car Back Into Service

Reactivation should be methodical: inspect, restore normal settings, and take a gentle shakedown drive to operating temperature while listening for anything unusual.

1. Exterior/interior: Remove the cover, check for rodent nests/chew marks (engine bay, cabin filter area), and look under the car for leaks.
2. Battery: Disconnect the maintainer and reconnect the negative terminal if you removed it; tighten properly. Expect to reset the clock and one-touch windows (consult the manual).
3. Tires: Set pressures to the door-jamb spec (bleed down if you overinflated). Remove wheel chocks.
4. Fluids and lights: Check oil level, coolant reservoir level, and washer fluid; test all exterior lights and wipers.
5. Start and drive: Start the engine and let it settle for 30–60 seconds, then drive gently for 20–30 minutes to full operating temperature. Light surface rust on rotors will clear with a few firm but safe stops.
6. Refuel: Top off with fresh fuel on your first drive; if you didn’t change oil before storage and are due by time or mileage, schedule it now.
7. EVs/hybrids: Verify SOC, connect to charge if needed, and apply software updates. Regen may be limited until the pack warms; that’s normal.

This approach catches any issues early and returns the vehicle to normal use without stressing components.

Climate and Storage Location Tips

Local conditions change the risk profile—cold increases flat-spotting and battery stress, heat accelerates battery and interior degradation, and humidity invites corrosion and mold.

• Cold climates: Ensure proper antifreeze protection. Performance tires are more prone to flat spots in cold; add cradles and avoid moving the car in extreme subzero temps until tires warm slightly.
• Hot/sunny climates: Prioritize shade, a UV-rated cover, and interior sunshades. For EVs, a 50–60% charge limit curbs heat-related battery aging.
• Humid/coastal areas: Use desiccants inside, keep the tank full, and consider a light underbody rinse before storage to remove salt; ensure the car is bone dry before covering.
• Apartment/HOA garages: Confirm rules for extension cords and maintainers. If outlets aren’t allowed, plan on disconnecting the negative terminal or using a jump pack on return.
• Solar maintainers: Only consider a quality, regulated solar maintainer if the panel gets consistent direct sun and you can connect to the battery posts. Avoid OBD-plug trickle devices.

Tailoring storage to your climate/location significantly reduces corrosion, battery stress, and interior damage.

Common Mistakes to Avoid

A few pitfalls account for most storage headaches. Steer clear of these to save time and money later.

• Setting the parking brake and returning to seized pads/shoes
• Leaving a near-empty gas tank and skipping stabilizer (gasoline)
• Using a non-breathable plastic tarp that traps moisture
• “Exercising” the engine with short idles that never reach full temperature
• Forgetting to isolate or maintain the battery (12V problems are the top post-storage failure)
• Storing key fobs near the car, causing parasitic wake-ups
• Placing toxic mothballs inside the cabin (hazardous fumes)
• Ignoring insurance/registration timing and potential storage options (e.g., comprehensive-only)

Avoiding these missteps is often the difference between a car that fires right up and one that needs a tow or repairs.

Summary

Three months is a manageable storage interval if you prepare methodically: clean and protect surfaces, stabilize and fill fuel (gas), support the battery with a maintainer or disconnection, manage tire pressures and brakes, secure the location, and shut down power-hungry features—especially on EVs. Don’t start the car unless you can fully warm it with a proper drive. On return, inspect, reset, pressurize tires, and take a gentle shakedown drive. These steps minimize risk, preserve value, and get you back on the road with minimal fuss.