Mechanic tools: names, pictures and what each one is used for

Where buying cheap is actually dangerous

Most tools on this page fail annoyingly. Two fail catastrophically, and they are the two that hold a car above you. A jack is a lifting device and not a supporting one: hydraulics leak, seals fail, and a jack that has held for an hour can drop in a second.

So the rule is absolute. Lift with the jack, then transfer the load onto axle stands rated above the weight, on level solid ground, with the wheels chocked. Never go under a car held only by a jack, and never trust a stand on tarmac in summer or on a slope.

Axle stands, always, in pairs

Rated well above the corner weight you are lifting. Set them on the manufacturer's jacking points, and shake the car before you go anywhere near it.

Chock the wheels still on the ground

A car in gear with the handbrake on can still roll once one axle is airborne. Chocks cost very little.

Check the jack's rating against the car

A two tonne jack is not lifting a whole car, it is lifting one corner. Loaded near its limit, a cheap jack creeps down.

Torque wrenches are safety kit too

Wheel nuts, brake calipers and suspension bolts all have specified torques. Guessing produces either a sheared bolt or a wheel that comes loose.

How to choose sockets and spanners

This is where most of the money goes and where quality is easiest to judge. The failure mode is always the same: the tool rounds the fastener, and then no tool will grip it.

Six point beats twelve point on tight fasteners

Six point sockets grip the flats. Twelve point grip nearer the corners and are far more likely to round a seized nut, in exchange for fitting at more angles.

Match the drive size to the job

Quarter inch for small fasteners and interior trim, three eighths for most engine work, half inch for suspension and wheels. Using a small drive on a big bolt breaks the ratchet.

Never use chrome sockets on an impact gun

Chrome vanadium is hardened to resist wear and shatters under impact. Impact sockets are softer, thicker and black for a reason.

Flare nut spanners for brake lines

An open spanner rounds a brake union almost immediately. A flare nut spanner wraps five of the six flats, and brake lines are not something to improvise on.

Buy a set, then buy singles

Unlike most trades, a socket set genuinely makes sense here because you need the whole range. Then replace the three sizes you use constantly with better ones.

Deep and shallow are not interchangeable

A shallow socket will not reach a nut on a long stud, and a deep one wobbles where clearance is tight. Sets that include both are worth the difference.

Diagnose before you dismantle

The single most expensive habit in home mechanics is replacing parts to see whether it helps. A basic diagnostic kit costs less than one wrongly guessed component and usually points straight at the fault.

An OBD reader tells you what the car has already noticed. A multimeter tells you whether a circuit is doing what the wiring diagram says. Between them they answer most electrical complaints without a single spanner.

Read the codes first, always

Even a cheap reader gives you a starting point and clears the guesswork. A stored code is the car telling you what it saw.

A code is a symptom, not a diagnosis

A sensor code frequently means a wiring or vacuum fault rather than a dead sensor. Replacing the named part is why people fit three sensors and still have the fault.

Test under load

Batteries, alternators and connections all read fine at rest and fail when asked for current. A clamp meter or a load test shows what a voltage reading hides.

Compression and vacuum before internals

Both are cheap and both tell you whether the problem is mechanical before anything comes apart.

What to buy first, in order

Stage one: service and wheels

A socket set with a ratchet and extensions, combination spanners, a torque wrench, a trolley jack, two axle stands and chocks. An oil filter wrench, a drain pan and a funnel. That covers a full service and a wheel change safely.

Stage two: brakes and diagnosis

An OBD reader and a multimeter. A brake bleeding kit and a caliper wind back tool. Flare nut spanners. Pliers, including circlip and hose clamp types. A breaker bar for whatever the last person overtightened.

Stage three: specialised and heavy

Impact wrench and impact sockets. Ball joint separator and hub puller. Spring compressors, which are the other genuinely dangerous item and often better hired. Timing tools for your specific engine, since they are never universal.

Mistakes that cost money

Going under a car on a jack

The mistake that kills people. Hydraulics fail without warning, and there is no second chance to reconsider.

Chrome sockets on an impact gun

They shatter, at speed, in your hand. Impact sockets exist specifically because the metallurgy has to be different.

Guessing torque on wheel nuts

Undertightened and a wheel works loose, overtightened and you stretch the stud or warp the disc. A torque wrench costs less than one wheel stud replacement.

Open spanners on brake unions

They round instantly, and then the line has to be cut and remade. A flare nut spanner is a few pounds.

Reusing stretch bolts

Torque to yield bolts on heads and big ends are designed to deform once. Reused, they fail, and the failure is expensive and sudden.

Replacing parts to diagnose

Cheaper to buy a reader and a multimeter once than to fit two sensors that were never the problem.

Looking after mechanic tools

Wipe oil off before storing

Old oil holds grit and water. A wiped socket set is a socket set you can still read the sizes on in five years.

Do not extend a torque wrench

A bar on the handle changes the reading completely, so the wrench is now lying to you. Use a breaker bar for undoing and the torque wrench only for tightening.

Wind torque wrenches back to zero

Storing one under spring tension slowly changes its calibration. Back it off after every use, and get it checked occasionally.

Keep sockets in a rail rather than a drawer

Loose sockets rolling in a drawer are how you lose the three sizes you use most.

Bleed and check the jack annually

Air in the hydraulics makes a jack spongy and unpredictable. If it creeps down under load, it is finished, not tired.

Frequently asked questions

What mechanic tools do I need to start?

A socket set with ratchet and extensions, combination spanners, a torque wrench, a trolley jack, two axle stands and wheel chocks, plus an oil filter wrench, drain pan and funnel. That covers a full service and a safe wheel change.

What is the difference between mechanic tools and automotive tools?

Nothing. They are two names for the same thing, and both terms are widely searched. Automotive is more common in the trade and in North America, mechanic more common in everyday use.

Can I use a jack to hold the car while I work under it?

No. A jack lifts, axle stands support. Hydraulic seals fail without warning and a jack that held for an hour can drop in a second. Lift, transfer the load to rated stands on level ground, chock the wheels, and shake the car before going near it.

Why can't I use normal sockets on an impact wrench?

Chrome sockets are hardened to resist wear, which makes them brittle under sudden impact, and they shatter. Impact sockets are made from a softer, tougher alloy with thicker walls, which is why they are black rather than chrome.

What is the difference between six point and twelve point sockets?

Six point sockets grip the flat faces of a fastener, so they are far less likely to round a tight or corroded one. Twelve point sockets fit on at twice as many angles, which helps in tight spaces, at the cost of gripping nearer the corners.

Do I really need a torque wrench?

Yes. Wheel nuts, brake components and suspension bolts all have specified torques, and both undertightening and overtightening cause failures that are dangerous rather than inconvenient. It is safety equipment as much as a tool.

What socket drive size should I buy?

Three eighths inch covers most engine and general work. Add quarter inch for small fasteners and interior trim, and half inch for suspension and wheel nuts. Using a small drive on a large bolt breaks the ratchet rather than the bolt.

Is a cheap OBD reader any good?

For reading and clearing fault codes, yes, and it is the single best value tool here. Cheap readers do not give live data or manufacturer specific codes, which is where a better one earns its money if you are diagnosing regularly.

Why did my brake union round off?

Almost certainly an open spanner. Brake unions are soft and thin walled, and an open jaw grips only two flats. A flare nut spanner wraps five of the six and is the correct tool for any brake or fuel line.

Can I reuse cylinder head bolts?

Usually not. Most modern heads use torque to yield bolts designed to stretch permanently once, so reusing them risks a failure under load. Check the manual for your engine, and if it specifies replacement, replace them.

What is a caliper wind back tool for?

Retracting the piston on a rear caliper that uses the handbrake mechanism, which screws in rather than pushing straight back. Forcing it with a clamp damages the mechanism and the seal.

Are spring compressors safe to use at home?

They are the other genuinely dangerous item here. A coil spring stores enormous energy and a slipping compressor releases all of it at once. Use proper caged compressors, or hire the job out. Many people who do their own suspension still do not do this part.