HomeBlogBlogA Practical Guide to the 5 Main Fluids in Your Car

A Practical Guide to the 5 Main Fluids in Your Car

What are the 5 main fluids in a car?

The five main fluids commonly checked in a car are engine oil, coolant, brake fluid, transmission fluid, and power steering fluid. Your vehicle may not use all five: many newer cars have electric power steering, and some transmissions have no owner-serviceable dipstick. Windshield washer fluid is also useful to keep topped up, even though it is not usually included in this group of five.

What does each fluid do?

Engine oil

Engine oil lubricates moving parts, helps control heat, and carries away contaminants. Check its level as directed in your owner’s manual, usually with the car parked on level ground. Use the specified oil grade; the wrong type can affect engine protection and performance.

Coolant

Coolant helps keep the engine from overheating or freezing and protects parts of the cooling system from corrosion. Check the reservoir only when the engine is cool, and use the coolant type specified for your vehicle. Never remove a hot radiator cap, because pressurized coolant can cause severe burns.

Brake fluid

Brake fluid transfers force from the brake pedal to the braking system. The reservoir level should stay within its marked range. If it is low or the brake warning light comes on, have the system inspected: a drop in level can signal worn brake components or a leak, and topping it off may not address the cause.

Transmission fluid

Transmission fluid lubricates and cools transmission parts and, in many automatic transmissions, helps transmit power. Checking procedures and fluid requirements vary widely. Follow the manual rather than relying on a universal fluid or dipstick method; some vehicles require service by a qualified technician.

Power steering fluid

Hydraulic power steering fluid helps the steering system operate smoothly. If your car has a fluid reservoir, check its level and use only the specified fluid. Many newer vehicles use electric power steering, which does not require this fluid.

How should you check and top up fluids?

Park on level ground and follow your owner’s manual for the correct checking conditions. Look for levels outside marked ranges, unusual discoloration, or signs of leaks. Don’t mix fluid types or guess at a replacement: specifications differ by vehicle. For a fuller step-by-step guide, visit our guide to checking and refilling essential car fluids.

FAQ

How often should you check your car’s fluids?

Check fluid levels at the intervals in your owner’s manual, and take a look before long trips. Check sooner if you notice a warning light, a leak, unusual smells, or a change in braking, steering, or engine temperature.