What Affects Brake Pad Life

• Driving style: late, hard braking wears pads fastest.
• Where you drive: stop-and-go traffic and hills wear pads faster than highways.
• Vehicle weight: heavier cars, SUVs and towing increase wear.
• Pad material: ceramic pads usually last longer than organic pads.
• Front vs. rear: front pads usually wear faster because they do most of the braking.

Pad Thickness Guide

Warning Signs

• A high-pitched squeal from the wear indicator
• Grinding, which means metal-on-metal contact
• A brake pad warning light on the dashboard
• Longer stopping distances or a soft pedal
• The car pulling to one side when braking

For a deeper look at the warning signs, read our guide on when to replace your brake pads.

Do You Need New Rotors Too?

Not always. Rotors are often replaced or resurfaced with the pads if they are worn below their minimum thickness, scored or uneven. A shaking steering wheel when braking is a common sign of rotor problems.

Frequently Asked Questions

How often should brake pads be checked?

Have them checked at every tire rotation or oil change. Many wheels let you see the outer pad through the spokes.

Should all four brake pads be replaced at once?

Pads are replaced in pairs on the same axle (both fronts or both rears). The front and rear do not always need doing at the same time.

How long does it take to replace brake pads?

For a garage, usually around an hour per axle, a little longer if the rotors are replaced too.

General Guidelines by Transmission Type

Always use the exact fluid specification in your manual. Transmissions are very sensitive to the wrong fluid type.

Signs Your Transmission Fluid Needs Attention

• Fluid that is dark brown or black, or smells burnt
• Harsh, delayed or slipping gear changes
• Whining or humming that changes with gear
• A red or pink puddle under the middle of the car

Fluid color is a good quick check. Our transmission fluid color guide shows what each shade means.

Fluid Change vs. Flush

A drain-and-fill replaces part of the fluid. A flush uses a machine to replace almost all of it. On high-mileage transmissions that have never been serviced, some mechanics prefer a gentle drain-and-fill over a flush. Ask your garage which they recommend for your car.

Frequently Asked Questions

Is lifetime transmission fluid really lifetime?

It usually means the life of the warranty or the expected life of the car under normal use. If you plan to keep the car a long time, or you tow or drive mainly in the city, changing the fluid is cheap insurance.

Can I check transmission fluid myself?

On many cars, yes, with a dipstick and the engine warm and running. Many newer cars have sealed transmissions with no dipstick, so a garage needs to check the level.

What happens if you never change transmission fluid?

The fluid breaks down and loses its ability to cool and protect, which increases wear and can lead to slipping and expensive repairs.

What the Cabin Air Filter Does

It cleans the air coming into the car through the heating and A/C vents, trapping dust, pollen, soot and debris. It is different from the engine air filter, which cleans the air going into the engine.

Signs Your Cabin Air Filter Needs Changing

• Weak airflow from the vents, even on high
• A musty or dusty smell when the fan is on
• Windows that fog up and are slow to clear
• More sneezing or allergy symptoms in the car
• Whistling from the vents

How to Replace It Yourself

On many cars, this takes about 10 minutes and no tools:

1. Find the filter housing, usually behind the glovebox (check your owner’s manual).
2. Empty the glovebox and release its stops so it swings down.
3. Unclip the filter cover and slide the old filter out. Note the airflow arrow.
4. Slide the new filter in with the arrow pointing the same way.
5. Refit the cover and the glovebox.

A musty smell can also come from the A/C system itself. See our guide to what different car smells mean: car smells like gas, burning or rotten eggs.

Frequently Asked Questions

Does the cabin air filter affect the A/C?

A clogged filter reduces airflow, so the A/C and heater feel weaker. It does not affect how cold the refrigerant gets, but less air reaches you.

Are carbon cabin filters worth it?

Activated carbon filters also reduce odors and some exhaust fumes. They cost a little more but are worth it if you drive in heavy traffic.

Is the cabin air filter the same as the engine air filter?

No. They are separate parts in different places, with different replacement intervals.

Typical Spark Plug Lifespan

Signs Your Spark Plugs Need Replacing

• Rough or shaky idle
• Engine misfires or hesitation when accelerating
• Harder starting, especially when cold
• Worse fuel economy
• Check engine light, often with a misfire code

Misfires can make the whole car vibrate. Read more about why your car might be shaking.

Why It Matters

Worn plugs need more voltage to fire, which strains the ignition coils, and they burn fuel less efficiently. Persistent misfires can also damage the catalytic converter, which is far more expensive than a set of plugs.

Can You Change Spark Plugs Yourself?

On many four-cylinder engines it is a straightforward DIY job with a spark plug socket and a torque wrench. On some V6 and V8 engines, the rear plugs are hard to reach, so a garage is easier. Always use the plug type and gap your manual specifies, and tighten to the correct torque.

Frequently Asked Questions

What happens if you never change your spark plugs?

Performance and fuel economy gradually drop, and eventually the engine misfires. Very old plugs can also seize in the cylinder head and become hard to remove.

Should I replace ignition coils with spark plugs?

Not automatically. Replace coils only if one is faulty, but inspect them and their boots while the plugs are out.

Do spark plugs affect fuel economy?

Yes. Worn plugs burn fuel less completely, so replacing them on time helps keep fuel economy where it should be.

Typical Oil Change Intervals

These are general ranges. Your manufacturer’s schedule takes priority, and some engines specify a particular oil grade and standard.

When to Change Your Oil Sooner

Manufacturers usually list a “severe service” schedule with shorter intervals. It often applies to normal everyday driving, such as:

• Mostly short trips where the engine does not fully warm up
• Stop-and-go city traffic
• Towing or carrying heavy loads
• Very hot or very cold climates
• Dusty or dirt roads

Why Oil Changes Matter

Oil lubricates moving parts, carries heat away and holds dirt in suspension until the filter catches it. Over time it breaks down and gets contaminated, which increases engine wear. Changing it on time is one of the cheapest ways to make an engine last.

Signs Your Car Needs an Oil Change

• The oil change reminder or oil life monitor says so
• The oil on the dipstick is dark and gritty, or the level is low
• Louder engine ticking or knocking
• An oil pressure warning light (stop and check the level right away)

Want to do it yourself? Follow our step-by-step guide to changing your oil.

Frequently Asked Questions

Is the 3,000-mile oil change rule still true?

Not for most modern cars. Better oils and engines mean most cars now go 5,000 miles or more between changes. Check your manual.

Should I change my oil if I barely drive?

Yes. Oil ages even when the car sits, so change it at least once a year, or as often as your manual says.

Can I switch from conventional to synthetic oil?

Yes, as long as the oil meets the grade and specification in your owner’s manual. You can switch back too.

How to Identify a Leak

Slide a sheet of white paper or cardboard under the car overnight. In the morning, check the color, smell, texture and where on the paper it dripped.

For more on fluid colors, see our transmission fluid color guide and our guide to checking car fluids.

Water Leaking Inside the Car

Damp carpets or water inside the cabin are not normal. Common causes include:

• Blocked A/C drain: condensation backs up and drips into the front passenger footwell.
• Clogged sunroof drains: water runs down the pillars and into the headliner or footwells.
• Worn door or window seals: water gets in during heavy rain or car washes.
• Leaking heater core: damp carpet with a sweet coolant smell and a foggy windshield.

Dry the carpets quickly to prevent mold and musty smells.

Frequently Asked Questions

Is it normal for my car to leak water after turning it off?

Yes. If you used the A/C, condensation can keep dripping for a while after you park.

Why is water dripping from my exhaust?

Burning fuel produces water vapor, which condenses in a cold exhaust. Small drips on startup are normal. Large amounts of white smoke and constant dripping once warm, with coolant loss, can point to a head gasket problem.

How do I know if it is coolant or water?

Coolant has a color (green, orange or pink), a sweet smell and a slightly slippery feel. Water has no color or smell. Also check whether the coolant level in the reservoir is dropping.

Smells That Need Attention Right Away

• Strong raw fuel smell, especially with a visible drip: fire risk. Do not smoke or run the engine, and have it checked before driving.
• Exhaust fumes inside the cabin: exhaust contains carbon monoxide. Open the windows and get the exhaust system checked promptly.
• Burning plastic or electrical smell: possible wiring short. Stop and switch off the engine.
• Hot, acrid smell with smoke from a wheel: a dragging brake. Stop and let it cool.

What Each Smell Means

Gasoline

A brief whiff right after refueling or on a cold start can be normal. A persistent smell can mean a loose or damaged gas cap, a leaking fuel line or injector, or a fault in the fuel vapor (EVAP) system. Check that the cap clicks shut, and look for drips under the car.

Rotten Eggs (Sulfur)

Usually a sign that the catalytic converter is not processing exhaust properly, often because of an engine running too rich or a converter that is failing. A battery that is overcharging can also give off a sulfur smell. Have it checked, especially if the check engine light is on.

Burning Rubber

A slipping drive belt, a loose hose resting on a hot engine part, or a brake that is dragging can all cause it. In manual cars, a burning smell after a hill start can be the clutch slipping.

Burning Oil

Oil leaking onto the hot exhaust, often from a valve cover gasket or oil filter, or spilled during an oil change. Check the oil level and look for leaks and blue-gray smoke.

Sweet, Syrupy Smell

This is coolant. If you smell it outside the car, look for a leaking hose or radiator. If you smell it inside, especially with a greasy film on the windshield, the heater core may be leaking. Watch the temperature gauge and the coolant level.

Musty or Mildew

Mold in the A/C evaporator, a clogged cabin air filter, or water leaking into the car. Replace the cabin air filter, and run the fan without the A/C for a few minutes before switching off to help dry the system.

Frequently Asked Questions

Is it safe to drive if my car smells like gas?

If the smell is strong or lasts more than a few minutes, no. Fuel leaks are a fire risk, so have the car inspected first.

Why does my car smell like gas when I start it?

A short smell on a cold start can be normal in older cars. If it lingers, or you notice it every time, have the fuel and EVAP systems checked for leaks.

How do I get rid of a musty smell in my car?

Replace the cabin air filter, check for wet carpets, and use an A/C system cleaner. If it persists, a garage can clean the evaporator.

Key Takeaways

• Grinding brakes are a safety issue. Get them inspected right away.
• Note when the noise happens (turning, braking, accelerating, over bumps) and which side it comes from.
• Recording the sound on your phone helps a mechanic diagnose it faster.

Noises When Turning

Noises When Braking

A light squeal on the first few stops on a damp morning is often just surface rust and is normal. A squeal that persists, or any grinding, means the brakes need inspecting. See our guide on when to replace your brake pads.

Noises When Accelerating

Noises at Idle

A squeal when the engine starts or the A/C switches on is usually a slipping drive belt. A ticking that speeds up with engine speed can be low oil or noisy valve lifters. Check the oil level first: our guide to checking car fluids shows how.

Frequently Asked Questions

Is a clicking noise when turning dangerous?

A clicking CV joint usually gives plenty of warning, but it will get worse and can eventually fail. Have it replaced soon rather than waiting.

Why does my car make noise when I turn the steering wheel while parked?

A groan or whine at low speed is often low power steering fluid or a worn pump. Many newer cars have electric power steering, where a faint motor whir is normal.

Why do my brakes squeak after rain?

Moisture forms a light layer of rust on the rotors, which the pads scrape off in the first few stops. If the noise disappears quickly, it is normal.

Diagnose by Symptom

Quick Checks Before You Call for Help

1. Check the lights. Turn on the headlights. If they are dim or do not come on, the battery is the likely problem.
2. Check the gear selector. Automatics only start in Park or Neutral. Move the lever firmly into Park and try again.
3. Check the steering lock. If the key will not turn, wiggle the steering wheel while turning the key.
4. Check the key fob. For push-button starts, a weak fob battery can stop the car recognizing the key. Most cars let you hold the fob against the start button. Check your owner’s manual for the exact spot.
5. Check the fuel gauge. It sounds obvious, but an empty tank is a common cause of cranking with no start.
6. Check the battery terminals. White or green corrosion, or a loose clamp, can stop the starter getting enough current.

How to Jump Start a Car Safely

1. Park the working car close by and switch both engines off.
2. Connect the red cable to the dead battery’s positive (+) terminal, then to the good battery’s positive terminal.
3. Connect the black cable to the good battery’s negative (–) terminal, then to a bare metal point on the dead car’s engine, away from the battery.
4. Start the working car and let it run for a few minutes, then try to start the other car.
5. Remove the cables in reverse order.

If the car starts with a jump but will not start again later, the battery may be failing to hold a charge, or the alternator may not be charging it. A parts store or garage can test both.

Frequently Asked Questions

How do I know if it is the battery or the starter?

A weak battery usually gives rapid clicking and dim lights, and a jump start fixes it. A bad starter usually gives a single click or no sound, while the lights stay bright, and a jump start does not help.

Why does my car start fine sometimes but not others?

Intermittent problems are often caused by loose or corroded battery connections, a failing starter, or a fuel pump on its way out. Note the conditions when it fails (hot, cold, after a short trip) to help your mechanic.

Can cold weather stop a car from starting?

Yes. Cold weather reduces battery power and thickens engine oil, so a battery that is already weak often fails on the first cold morning.

Key Takeaways

• Note exactly when the shaking happens (speed, braking, idling, accelerating). It narrows the cause down quickly.
• A flashing check engine light with shaking means the engine is misfiring. Reduce speed and get it checked right away.
• Sudden, violent shaking can mean a loose wheel or a failing tire. Pull over safely and inspect before driving on.

Quick Diagnosis Table

1. Unbalanced or Damaged Wheels and Tires

The most common cause of a steering wheel that vibrates at highway speed. Wheels lose their balance weights over time, and potholes can bend a rim or damage a tire. A tire shop can rebalance the wheels quickly and cheaply. Also check for bulges in the sidewalls or uneven wear, which can cause vibration too.

2. Warped or Unevenly Worn Brake Rotors

If the steering wheel or brake pedal pulses when you slow down, the rotors are probably uneven. The usual fix is resurfacing or replacing the rotors, normally together with new pads. See our guide on when to replace your brake pads.

3. Sticking Brake Caliper

A caliper that does not release keeps one brake slightly applied. You may notice a burning smell, the car pulling to one side, or one wheel much hotter than the others after a drive. Have it repaired promptly: it wears out pads and rotors and can overheat the brakes.

4. Engine Misfire

Worn spark plugs, a failing ignition coil, or a fuel or vacuum problem can make one cylinder misfire. The car shakes most at idle and under load, and the check engine light usually comes on. A diagnostic scan will show which cylinder is misfiring.

5. Worn Engine or Transmission Mounts

Mounts are rubber blocks that absorb engine vibration. When they wear out, you feel more vibration at idle (especially in Drive), and you may hear a clunk when you shift or accelerate.

6. Worn CV Axle

A worn inner CV joint often causes vibration when accelerating. A worn outer joint usually clicks when you turn. A torn rubber boot lets grease out and dirt in, so check the boots for grease spray around the inside of the wheel.

7. Suspension and Steering Wear

Worn tie rod ends, ball joints, wheel bearings or shocks can cause shaking, wandering and uneven tire wear. These are safety-critical parts, so have them inspected if the shaking comes with clunks or loose steering.

8. Loose Lug Nuts

If a wheel was recently removed and the car suddenly starts shaking or wobbling, stop and check the lug nuts. A loose wheel can come off. Tighten the nuts to the specified torque or have the car towed to a garage.

Frequently Asked Questions

Is it safe to drive a car that is shaking?

Mild vibration at a particular speed (usually wheel balance) is not an emergency, but get it checked soon. Sudden or violent shaking, shaking with a flashing check engine light, or shaking after a wheel change is not safe: stop and investigate.

Why does my car shake at 60 mph but not at lower speeds?

Wheel imbalance shows up in a specific speed range, often around 50 to 70 mph. Rebalancing the wheels usually fixes it.

How much does it cost to fix a shaking car?

It depends on the cause. Wheel balancing is one of the cheapest fixes, while rotors, CV axles and engine mounts cost more. A garage can usually pin down the cause with a short test drive and an inspection.