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Go With the Flow: A Guide to Your Car’s Liquids

By Graham Heeps

Your vehicle is full of liquid assets: fluids that keep systems functional, well-lubricated, cool and clean. Modern cars and trucks are simpler to maintain than before when owners were expected to top up various liquids regularly. Thanks to advanced components and system replacements such as hydraulic power steering, there are fewer fluids to monitor. Nevertheless, here are some of those essential fluids.

Engine oil

Not sure when to change the oil? Follow your manufacturer’s recommendation in the service schedule, even in cold conditions. For a Honda CR-V, for example, that means a change roughly every 10,000 km. Consider using synthetic rather than conventional mineral oil. Synthetics are better at combatting deposit buildup, reducing wear and protecting against high temperatures.

Brake fluid & coolant

If you notice a low level of either of these fluids, or if a warning light comes on, it’s likely symptomatic of a bigger problem. Low brake fluid could mean a leak that requires immediate attention to maintain safe braking. As for radiator coolant, “if your vehicle indicates it’s running hot, it’s best to stop right away,” says Randy Loyk, AMA’s chief mechanic.

Diesel exhaust fluid

This fluid, typically called DEF, helps clean up the exhaust systems of newer diesel cars and trucks. Essentially, it helps reduce the amount of air pollution that is created by vehicles that have diesel engines. All of these vehicles have a gauge that monitors the level of DEF. When you hit one-quarter on the gauge, that will serve as your cue to fill up at the next fuel stop.

Transmission fluid

You likely won’t find a transmission-fluid dipstick on most late-model vehicles. Hence, maintenance involves watching for a warning light or a burning smell, and monitoring for leaks. As with brake fluid and coolant, transmission fluid changes will be factored into the vehicle’s maintenance schedule. This is usually every 40,000 to 100,000 km, depending on how often you drive your vehicle. 

Windshield washer

It may seem obvious but keeping the windshield washer topped up is easy to do and crucial for safe driving year-round. “If you choose to use a summer windshield washer fluid to help remove bugs, put the antifreeze fluid back in earlier than you think you should,” Loyk says. “Even a few ice crystals on a frosty October morning can crack the hose or the washer nozzles on your hood.”