Replacing Filters and Inspecting Fluids

All the filters in your vehicle share one goal: to keep contaminants out of vital systems. These parts work quietly behind the scenes, but they’re essential for performance, fuel economy, and even cabin comfort. 

Let’s break down the main types. 

Purpose: Keeps dirt, dust, and debris from entering your engine. 

• Symptoms of a dirty filter: Reduced acceleration, decreased fuel efficiency, black smoke from the exhaust. 
• Replacement interval: Generally every 20,000–24,000 km, but always check your owner’s manual. 

A clogged engine air filter restricts airflow to your engine, forcing it to work harder. This not only affects performance but can increase fuel consumption. Replacing it is usually a quick DIY job—pop the hood, open the air filter housing, remove the old one, cringe at its condition, and drop in the new one. 

Purpose: Prevents dust, pollen, and pollutants from the air entering your vehicle’s cabin. 

• Symptoms of a dirty filter: Weak airflow from vents, musty odours, fogged windows. 
• Replacement interval: Around every 20,000 km or once a year. 

If you suffer from allergies or drive in urban areas with lots of dust and exhaust fumes, changing the cabin air filter regularly makes a big difference in air quality. Replacing your air filters is a simple job that makes all the difference. 

Purpose: Cleans debris from engine oil to protect moving parts. 

• Symptoms of a dirty filter: Loss of engine power, sputtering, rough idling, or vehicle stalling due to inconsistent oil flow. 
• When it’s replaced: Every time you change your oil. 

An oil change is a package deal: You can’t replace the oil filter without also changing the oil. Skipping this step means your new oil will run through a dirty filter, defeating the purpose of your oil change altogether. 

Purpose: Removes impurities from fuel before it reaches the engine. 

• Symptoms of a dirty filter: Difficult starts, rough idling, poor acceleration (including surges while accelerating), frequent stalling, and decreased fuel efficiency. 
• Replacement interval: varies widely. Some fuel filters last through the lifetime of your vehicle, while others require regular replacement. Check your owner’s manual for the fuel filter replacement intervals of your vehicle. 

A dirty fuel filter can largely limit your engine’s performance. If you’re experiencing any of the classic symptoms or it’s been a while since your last check, it might be time to inspect or replace your fuel filter. 

Automotive fluids are the lifeblood of your car. They lubricate, cool, clean, and power various systems. By regularly inspecting and topping up (or flushing) these fluids, you can help them to keep your car in top shape. 

Purpose: Lubricates engine parts, reduces friction, and carries away heat and contaminants. 

• Symptoms of old or low oil: Knocking noises, engine overheating, sluggish performance, or a lit oil warning light. 
• Replacement interval: First, follow your vehicle manufacturer’s guidelines.Recently manufactured vehicles may be able to drive more than 12,000 km before needing an oil check. General guideline, though, is 5,000–8,000 km. 

Dark, sludgy engine oil or low oil levels can cause engine wear or even complete engine failure. Don’t wait for warning signs. A quick check of your dipstick could save your engine and help you gauge how long you can go between oil changes. 

Purpose: Keeps your transmission components cool and shifting smoothly. 

• Symptoms of dirty or low fluid: Gear slipping, delayed shifting, rough gear changes, or a burned smell. 
• Replacement interval: Typically 50,000–100,000 km, but always check your owner’s manual. 

Low or degraded transmission fluid can lead to gear slippage, delayed shifting, or full transmission failure, which is one of the priciest repairs out there. 

Purpose: Regulates engine temperature, prevents freezing, and protects against corrosion. 

• Symptoms of low or dirty coolant: Overheating, sweet smells from the engine bay, visible leaks, or poor cabin heat. 
• Replacement interval: Every 2–5 years, or as recommended for your vehicle. 

Never open a radiator cap while the engine is hot. If the coolant level is low, add a 50/50 mix of coolant and distilled water unless your car requires premixed fluid. 

Purpose: Transfers force from your brake pedal to the brakes for safe stopping. 

•  Symptoms of contaminated fluid: Soft or spongy brake pedal, decreased braking power, warning lights. 
• Replacement interval: Every 2–3 years. 

Brake fluid absorbs moisture over time, which can corrode your system and reduce braking effectiveness. Keep brake fluid clear for safe and comfortable stopping. 

Purpose: Makes steering smooth and responsive by pressurizing the system. 

•  Symptoms of low fluid: Whining noises, stiff or jerky steering, or visible leaks. 
• Replacement interval: Usually only when there’s a leak—many modern cars use electric power steering instead. 

In modern vehicles using electric power steering, you won’t have to worry about power steering fluid at all. If your vehicle uses hydraulic steering, keeping the fluid level in check can save you from costly pump or rack repairs.
 

Purpose: Clears dirt, bugs, salt, and debris from your windshield for better visibility. 

•  Symptoms of low fluid: Weak spray or no spray from washer jets. 
• Replacement interval: Top up as needed, especially before long drives or during winter weather. 

Beyond its convenience, washer fluid is a safety feature. Keeping your windshield clear is vital for visibility, especially in poor weather. 

Plan your routine ahead of time so you don’t suddenly remember in the middle of a road trip or your commute that too long has passed since you last checked your fluids or filters. Follow these tips to create your personalized inspection routine. 

• Set a schedule: Check your fluids monthly and replace filters as recommended. 
• Purchase the right products early: Always use vehicle-specific filters and fluid types. Check labels or your manual. 
• Stay clean: Use gloves and rags, especially when dealing with oil or transmission fluid. 
• Keep records: Log filter changes and fluid top-ups so you stay on track and can spot trends. 

Many filter replacements and fluid checks are DIY-friendly. But some fluid flushes—like transmission or brake fluid—are best left to certified technicians with the proper tools and disposal systems. If you’re ever unsure or uncomfortable with filter and fluid management, it’s worth the peace of mind to let professionals handle it. 

Additionally, if you notice recurring low fluid levels, strange smells, unusual engine sounds, or warning lights on your dashboard, those are signs something more complex may be wrong. A diagnostic from a trusted mechanic can prevent small problems from becoming costly disasters. 

Replacing filters and inspecting fluids might not get as much attention as brake repairs or tire rotations, but they’re just as crucial in keeping your car running well. Regular attention to these simple components helps you catch issues early, save on fuel, protect your engine, and ultimately extend your vehicle’s lifespan. 

If you need the right tools to get the job done, or want advice before popping the hood, visit your local NAPA Auto Parts store and chat with our experts.