Fluids are the lifeblood of any car. Without the right coolant, oil, brake fluid or transmission fluid, the engine overheats, brakes fail or the gearbox grinds. Most drivers only think about oil changes, but a well‑kept fluid system saves money, avoids breakdowns and keeps performance on point.
In this guide we’ll walk through the most common fluids, why they matter, and how you can check and refill them yourself. No fancy jargon – just the steps you need to keep your ride happy.
Engine oil lubricates moving parts, reduces wear and carries heat away from the combustion chamber. Use the grade your manufacturer recommends – usually 5W‑30 or 0W‑20 for modern cars.
Coolant (antifreeze) keeps the engine from boiling in summer and freezing in winter. A 50/50 mix of water and ethylene‑glycol or propylene‑glycol is standard, but some cars need a specific formula.
Brake fluid transfers the pressure you apply on the pedal to the brakes at each wheel. It must stay clean and at the right level; old fluid absorbs moisture and can cause spongy brakes.
Transmission fluid (ATF for automatics, gear oil for manuals) protects gears, cools the gearbox and ensures smooth shifting. Different transmissions need different specs – check your manual.
AC refrigerant (R‑134a or R‑1234yf) is the gas that makes the cabin cool. It’s not a fluid you top up like oil, but a leak or low charge will make the AC blow warm air.
Start with a clean rag, a flashlight and a quick glance at each reservoir. Most cars have colour‑coded caps – oil is usually black or amber, coolant is green, red, or orange, and brake fluid is clear‑to‑amber.
For oil, pull the dipstick, wipe it clean, re‑insert, then pull again. The level should sit between the two marks. If it’s low, add the recommended oil a little at a time, re‑checking until it’s right.
Coolant checks are similar: locate the overflow tank, make sure the engine is cool, and look at the “full” and “low” lines. Top up with a pre‑mixed solution or mix your own, but never open the radiator when hot.
Brake fluid is a bit trickier. The reservoir is often translucent, so you can see the level without opening it. If it’s low, use the exact type (DOT 3, DOT 4, or DOT 5.1) your car calls for – mixing types can damage the system.
Transmission fluid checks vary. Some cars have a dipstick under the hood, others require a shop‑level check. If you see a burnt smell or a frothy appearance, it’s time for a change.
When it comes to AC refrigerant, you’ll need a recharge kit and a pressure gauge. If the system is low, follow the kit instructions carefully – overcharging can damage the compressor.
Regularly schedule full fluid replacements according to the owner’s manual – typically every 30,000‑60,000 miles for oil, 2‑3 years for coolant, and every 2 years for brake fluid. Keeping a simple log in your garage helps you stay on top of it.
Bottom line: a quick visual check every month and a proper top‑up when needed can prevent costly repairs. Your car will thank you with smoother rides, cooler engines and safer brakes.
