Mustang Spring Startup Checklist: Waking It After Winter

Before you turn the key on a Mustang that sat all winter, walk around it, look under the hood for rodent damage, remove anything you stuffed in the exhaust or intake, check the battery, tire pressures and fluid levels, and then make the first drive a gentle one. Here's the full sequence, plus what's normal and what's not once it's running.

Before you touch the key

Most spring-startup problems are found before the engine ever runs, so take ten minutes for an inspection first.

Walk-around

• Remove the reminders. If you plugged the exhaust tips or intake with steel wool or a rag, pull it out now. Starting a car with a blocked exhaust is a real and avoidable problem.
• Look under the car for fresh drips or puddles on the floor. Note the color: brown or black (oil), green, orange, pink or yellow (coolant), red (automatic transmission fluid or power steering fluid on older cars), clear and slick (brake fluid, which is serious).
• Check the tires for obvious low pressure, cracking in the sidewalls or tread, and bulges.

Under the hood: look for uninvited guests

Open the hood with a flashlight. Signs that mice moved in over the winter:

• Shredded insulation, leaves, seeds or nest material on top of the engine, around the battery or in the cowl area under the wipers
• Droppings on the engine cover or strut tower
• Chewed wiring, vacuum lines or washer hoses

Open the air filter box and look at the filter. A nest there will choke the engine and can be pulled into the intake. Do the same with the cabin air filter if you can reach it. If you find chewed wires, don't start the car until they're repaired. A damaged sensor wire can cause confusing warning lights; a damaged power wire can be a fire risk.

Battery: test it before you crank

If the car spent the winter on a smart maintainer, the battery should be ready. Disconnect the maintainer before starting. If the battery was disconnected or left unattended, check it:

These numbers are typical for standard 12-volt lead-acid and AGM batteries; exact figures vary a little by type and temperature. A battery that was drained flat for months often won't hold a charge anymore. If it cranks slowly after a full charge, see our guide to choosing a replacement battery. On newer Mustangs, a weak battery can also cause odd electrical behavior, flickering screens and random warning messages that disappear once voltage is healthy.

Tires: reset pressure to spec

If you raised the pressure for storage, set it back to the figure on the driver's door-jamb placard, measured cold. Tires also lose some air naturally over months. The TPMS warning may come on if pressures are low; it should clear after you correct the pressure and drive a short distance.

Check the date code on the sidewall too. It's a four-digit number at the end of the DOT code (for example, 2219 means the 22nd week of 2019). Performance tires that are several years old can be hard and lose grip even with plenty of tread. If you're due, our tire buying guide helps you pick the right type.

Fluids: five quick checks

1. Engine oil. Check the dipstick with the car level and the engine cold. If you didn't change the oil before storage, plan to change it soon after the first drive, since it has been sitting with moisture and acids for months.
2. Coolant. Check the level in the reservoir (degas bottle) against the marks, engine cold. Never open the cap on a hot engine.
3. Brake fluid. The level should sit between MIN and MAX. A noticeable drop since fall points to a leak or very worn pads.
4. Washer fluid. Top up for spring pollen and bugs.
5. Power steering fluid on older Mustangs with hydraulic steering. Mustangs from about the 2011 model year on use electric power steering, so there's no reservoir to check; if you don't see one, that's why.

The first start

• Start it outside or with the garage door fully open. Never run the engine in a closed space.
• Let it idle for a minute while you watch the gauges or cluster: oil pressure warning off, no temperature warning, and charging normal.
• Expect a bit of white vapor from the exhaust and maybe a drip of water from the tailpipe. That's condensation, and it clears as the exhaust warms up. Thick, sweet-smelling white smoke that doesn't go away is not normal and can point to coolant being burned.
• A light lifter or valvetrain tick in the first seconds is common on a car that sat. It should fade as oil pressure builds. A tick that stays or a knock that gets louder needs attention.

If the check engine light stays on after startup, don't panic. A battery that was drained or disconnected can trigger codes, and so can a nest-damaged sensor. Read the code before guessing. Our check engine light guide walks through what to do first.

The first drive

Treat the first ten miles as a shakedown, not a pull to redline:

• Brakes first. A thin layer of surface rust on the rotors is normal after storage and usually scrubs off after a few gentle stops. You may hear a grinding or scraping sound for the first stop or two. A pull to one side, a pedal that feels soft, or noise that doesn't go away needs inspection before spirited driving.
• Feel for vibration. Flat spots from sitting usually smooth out after several miles. Vibration that remains may be a wheel balance or tire issue.
• Watch the temperature gauge once the engine is fully warm and in traffic, so you know the fan and thermostat work.
• Listen for squeals from the serpentine belt. Belts can take a set or glaze after months; a brief chirp on a cold start is common, a constant squeal isn't.

After the first drive: plan the season

Back home, check again for leaks under the car and recheck tire pressure. Then make a short list for the coming season: an oil change if it's due by time, wiper blades, and anything you noticed on the drive.

This is a good moment to update your service history. In My Mustang, log the startup as a record with notes on anything odd (a weak battery reading, a chewed hose), attach a photo, and set reminders for the next oil change and the next storage season. If you plan to put the car away again in the fall, keep our winter storage checklist handy.

Frequently asked questions

Is surface rust on Mustang brake rotors after winter normal?

Yes. A light orange layer forms on cast-iron rotors whenever a car sits, especially in humid storage. It usually wears off after a few gentle stops. Deep pitting, grinding that does not go away, or a pulsing pedal need an inspection.

Do I need to change the oil after winter storage?

If you changed it right before storage and the car sat less than about six months, you can usually keep running it. If the oil was already used when the car was parked, change it soon after the first drive.

Why is my check engine light on after winter storage?

Common causes include a battery that was drained or disconnected, a loose fuel cap or filler, and wiring chewed by rodents. Read the trouble code first to see which system it points to.