6 Essential Car Fluids and How to Check Them

The six common checks are engine oil, coolant, transmission fluid, brake fluid, hydraulic power-steering fluid where fitted, and windshield-washer fluid. Use the exact owner’s manual because locations, temperatures, procedures and fluid specifications vary.

Never open a hot pressurized cooling system, and do not improvise a transmission level check on a sealed unit.

Quick reference

Fluid	Basic check	Stop and investigate when
Engine oil	Level ground; follow the dipstick or electronic procedure	Warning light, rapid loss, metal, coolant contamination or abnormal pressure
Coolant	View the reservoir only under the manual’s safe conditions	Overheating, repeated loss, leak or contamination
Transmission fluid	Use the exact dipstick or temperature/level-plug procedure	Slip, shudder, delay, leak, overheat warning or codes
Brake fluid	Inspect reservoir level without introducing dirt	Low level, warning lamp, leak, changed pedal feel or contamination
Power-steering fluid	Check only if the vehicle has a hydraulic system	Noise, heavy steering, leak or foaming
Washer fluid	Fill the labeled reservoir with an appropriate product	Leak, frozen system or pump/nozzle fault

Ford’s under-hood overview for one current vehicle shows how these reservoirs and checks vary by engine and equipment.¹

1. Engine oil

Park as directed, wait the specified time, then use the dipstick or electronic display. The level should be within the indicated range; overfilling is not a solution. Add only the permitted viscosity and specification.

2. Engine coolant

Check the reservoir at the temperature specified in the manual. Never remove a hot pressurized cap. Use the exact coolant chemistry and concentration; color alone does not prove compatibility.

3. Transmission fluid

Some vehicles have a dipstick. Others require a lift, level plug, scan data and a narrow temperature range. Low fluid usually indicates a leak. Use only the exact specification.

4. Brake fluid

Check the translucent reservoir against its marks without opening it unnecessarily. A falling level can accompany pad wear or a leak and needs inspection. Do not mix an unspecified fluid or contaminate the reservoir.

Inforca’s current portfolio lists PureGuard DOT 3 and DOT 4 brake fluids, but the vehicle requirement must be confirmed before product selection.²

5. Power-steering fluid

Many newer vehicles use electric power steering and have no reservoir. Hydraulic systems may specify a dedicated fluid or a particular ATF. Read the cap and manual; do not assume.

6. Windshield-washer fluid

Use the labeled washer reservoir and a fluid suited to expected temperatures. Washer fluid is not coolant, and plain water can create freezing, deposits or cleaning limitations.

Frequently asked questions

Should all six fluids be topped off at every oil change?

They should be inspected as specified. Repeated loss requires diagnosis, not repeated topping off.

Can fluid color identify the product?

No. Use documentation and labels.

Can used fluids go down a drain?

No. EPA identifies engine oil, transmission fluid, power-steering fluid, brake fluid and antifreeze as motor-vehicle wastes that can contaminate groundwater.³

Does every car have power-steering fluid?

No. Electric systems do not use a hydraulic reservoir.

Build a vehicle-specific checklist

Use the owner’s manual to record reservoir locations, check conditions and exact specifications. Shops can send Inforca the documented requirements, monthly volume and package needs to compare currently supported MANNOL and PureGuard products.

Sources

Footnotes

1. Ford Motor Company, 2025 Super Duty Under-Hood Overview, accessed September 10, 2026. ↩

2. Inforca International, Products, accessed September 10, 2026. ↩

3. U.S. Environmental Protection Agency, Motor Vehicle Waste Disposal Wells, accessed September 10, 2026. ↩