How to Maintain Car Keys and Locks
Car keys and locks are maintained by keeping the key blade clean and straight, the fob dry with a fresh battery, and each lock clean and lubricated as the handbook of the car states.
Inta-Lock Car Key Guides. Updated October 2026.
A key and its lock wear as a pair, so care for one protects the other. The routine below is set out part by part, the blade, the fob, the battery, the spare key and the door, boot and ignition locks, each with the sign that care has stopped being enough.
The handbook of the car names the lubricant for its locks and how often they are serviced, and a worn blade is replaced from the key code and not copied. The spare key gets the same care as the key in daily use, because it is the key that stands in when the first one fails.
How Are Car Keys and Locks Maintained?
Car keys and locks are maintained by three habits, a clean and straight key blade, a dry fob with a healthy battery, and locks that are kept clean and lubricated as the handbook of the car states.
A car key is two things in one case. The metal blade is a mechanical part that turns the door lock and, on many cars, the ignition lock. The fob is an electronic part, with a battery, button switches and a circuit board. Each half has its own care.
A lock is a set of small sprung parts that the cuts of the blade lift into line. Grit, dried lubricant and a blade with rounded cuts all stop those parts moving freely. A key and its lock are therefore maintained together.
The routine asks for a cloth, the lock lubricant the handbook of the car names and a new battery of the type the fob takes.
What Does a Car Key and Lock Care Routine Include?
A car key and lock care routine covers seven parts, and each part has its own care, its own moment and its own sign that care is no longer enough.
| Part | Routine care | When the care is done | Sign that care is no longer enough |
|---|---|---|---|
| Key blade | Wiped with a dry cloth and checked for a bend or a crack | Whenever the blade looks dirty | Rounded cuts, a bend, a crack near the head, or a turn that takes a jiggle |
| Fob case and buttons | Wiped with a barely damp cloth, seam and button pad checked for splits | After any drop on a hard surface | A split case, a torn button pad or a blade that wobbles in the case |
| Fob battery | Replaced with a new cell of the type printed on the old one | At the first sign of a weak remote | A new battery changes nothing, or the range stays short |
| Spare key | Used to lock, unlock and start the car, then stored dry and away from the front door | From time to time, while the first key still works | The spare no longer starts the car or its buttons do nothing |
| Door lock | Keyway blown clear of dust, given the lubricant the handbook names, then worked with the key | At the interval the handbook of the car states, and when the key starts to drag | The key still drags, sticks or turns part way after cleaning |
| Boot lock | The same care as the door lock, where the boot carries a keyway | At the interval the handbook of the car states | The lock turns and the boot stays shut |
| Ignition lock | Used only with a clean, straight key | Every day the car is driven | The key sticks or turns only after a wiggle |
The last column marks the point where the key or the lock has a fault and care at home ends. For work on a fault, a quote is agreed before work begins.
How Is a Car Key Fob Kept Working?
Four habits keep a car key fob working, a fresh battery, a dry case, a soft landing and a place away from heat.
- A fresh battery. A fob battery is a small coin cell that weakens gradually. A shorter range, a second press of the button or a warning on the dashboard are the signs, and the cell is replaced with the type printed on the old one.
- A dry case. A fob is protected from moisture. Water does its damage on the circuit board, not on the plastic, and a fob that misbehaves after a soaking has a fault that care does not reverse.
- A soft landing. A drop on a hard floor cracks the case, loosens the battery contacts and breaks solder joints on the board. A silicone cover over the fob absorbs the knock.
- A place away from heat. A fob is protected from high temperatures. A dashboard in summer sun and a radiator shelf are the two hot places a key is most easily left.
The old battery is a safety matter in a home with children. The Office for Product Safety and Standards names car key fobs among the products that hold button batteries in its button battery safety campaign, and it warns that a swallowed button battery is able to badly injure or kill a child.
The same guidance states that a dead button battery still holds enough power to badly hurt a small child, and that spare button batteries are stored securely and out of the reach of children. A button battery that is removed is stored securely and recycled properly and promptly, so the spent cell from a fob goes to a battery recycling point and not into a drawer.
A car key that drags, a fob that has gone quiet or a lock that stays stiff after cleaning? Matt attends the work himself, and what applies to the car is confirmed on the call.
Call Matt on 0116 442 2084How Is a Car Door Lock Cleaned and Lubricated?
A car door lock is cleaned first and lubricated second, with the lubricant the handbook of the car names, in the five steps below.
- Find the keyway and the lock care page of the handbook. On a car with a remote or keyless key the door lock often sits under a cap on the driver door handle, and the handbook of the car shows how the cap comes off and names the lubricant for the lock.
- Blow the keyway clear with a short burst of compressed air, so dust and grit leave the lock before any lubricant goes in.
- Give the keyway a small amount of the lubricant the handbook names. With a dry lock lubricant that is one short puff of graphite powder or one short burst of a dry PTFE spray.
- Slide the key blade in and out several times and turn it both ways, so the lubricant reaches the moving parts of the lock.
- Wipe the blade and the area around the keyway with a dry cloth, so no residue reaches a pocket or the paint.
The dry lubricant rule is the common lock care rule that a lock takes a product that dries, because a wet film holds dust and the paste that forms stiffens the lock. The handbook of the car has the final word, and a product the handbook names for its locks is the right one for that lock.
What Shortens the Life of Car Keys and Locks?
Three habits shorten the life of car keys and locks, and each one is a matter of force or the wrong product.
- The key used as a tool. A blade that opens parcels, lifts tin lids or scrapes ice bends and chips. A bent blade lifts the parts of the lock unevenly and wears them.
- Force on a stiff lock. A key that is forced round twists at its thinnest point and snaps there. A stiff turn is a sign to clean the lock and check the blade.
- The wrong product in the keyway. A general purpose oil or grease that the handbook of the car does not name for its locks stays wet in the keyway, and dust clings to a wet film.
A heavy key ring is a separate matter. Its weight hangs from the key while the key sits in the ignition lock, and the handbook of the car states any limit on what is carried with the key.
When Is a Worn Car Key Replaced?
A worn car key is replaced when the blade shows rounded cuts, a bend or a crack, or when it turns the lock only after a jiggle while the spare key turns the same lock cleanly.
The spare key is the test. A spare that turns the door lock and the ignition lock without effort shows that the first blade is the worn part. A spare that drags in the same way points to the lock.
Cleaning does not put metal back on a blade. Rounded cuts lift the parts of the lock to the wrong height, and each turn wears both further.
A worn key is not copied, because a copy carries the wear across to the new blade. The blade is cut to the key code or to the decoded lock instead, so the new key matches the lock as it was built. That work is car key cutting, and a quote is agreed before work begins.
How Is a Spare Car Key Kept Ready?
A spare car key is kept ready by using it from time to time, keeping a healthy battery in its fob, and storing it dry and away from the front door.
Locking, unlocking and starting the car with the spare key shows that the blade, the remote and the chip inside the key all still work.
Storage is a security matter as well as a care matter. Thatcham Research, in its advice on car security, recommends a signal blocking pouch for storing keys, spares included, on cars with keyless entry.
The same advice covers a car bought used with one working key. Thatcham Research recommends that the missing keys are deleted and a spare key is added as soon as possible.
Which Problems Sit Beyond Routine Key and Lock Care?
Five situations sit outside routine care of a car key and its lock, and each one has a different answer.
How Does Key Fob Maintenance Differ From Key Fob Repair?
Key fob maintenance keeps a working fob working, while key fob repair restores a fob that has already failed. A dead button, a cracked case or a remote that stays silent with a new battery is a fault.
A fault is traced to the part that failed, the switch, the contacts, the board or the case. That is the work of key fob repair, carried out at the vehicle.
What About Rust on the Key Blade?
Rust on a blade is past the reach of a dry cloth. Light surface rust comes off with care and deep pitting does not, and the steps and the limits are set out in the guide on how to remove rust from car keys.
Why Does a Lock Stay Stiff After Lubrication?
A lock that is clean, lubricated and still stiff with a sound key has worn or seized parts inside. More lubricant does not free it. The lock is repaired or rekeyed, which belongs to car door lock repair.
What About a Frozen Door Lock in Winter?
A frozen lock is a lock with water in it, and the water has turned to ice. The handbook of the car states how its locks are thawed and which product suits them. Force on the key does not clear ice, and a blade that is forced is a blade that snaps.
A remote key leaves the mechanical door lock unused for long periods, so the state of that lock stays unknown until the day the blade is used. Turning the lock with the blade from time to time shows its state while the remote still works.
Why Does a Cared for Key Still Fail?
A clean key with a new battery that still leaves the door shut has a cause beyond maintenance. The battery of the car, the remote signal and the lock itself are checked in turn, and those checks are listed for a key that fails to unlock the door.
When care has run its course on a car key or a lock in Leicester, the call to Matt is answered 24 hours a day.
Frequently Asked Questions
How often are car door locks lubricated?
Car door locks are lubricated at the interval the handbook or the service schedule of the car states, so no single interval applies to every car.
A key that starts to drag in a lock is the sign that the lock is due for cleaning, whatever the date.
Which lubricant suits a car door lock?
The lubricant that suits a car door lock is the one the handbook of the car names for its locks.
The two dry lock lubricants are graphite powder and dry PTFE spray, and both leave a dry film that does not hold dust.
Is a general purpose oil spray safe in a car lock?
A general purpose oil spray belongs in a car lock only where the handbook of the car names it for the locks.
An oil film stays wet inside the lock, and dust clings to a wet film.
How long does a car key fob battery last?
The life of a car key fob battery depends on the type of key, how often the buttons are pressed and how the key is stored, so no single figure applies.
A shorter range and a second press of the button are the signs that the cell is near its end.
Does a heavy key ring damage the ignition lock?
A heavy key ring hangs its weight from the key while the key sits in the ignition lock, and the handbook of the car states any limit on what is carried with the key.
No wear figure is given here, because no handbook or official source read for this guide states one. A car key on a ring of its own carries no extra weight.
How much does it cost to replace a worn car key?
The cost of replacing a worn car key is quoted for the individual key, and a quote is agreed before work begins.
The key type, the blade type and whether the new key has a chip or a remote to program all move the figure. No price list is published.