Fluid Changes

As part of a regular maintenance schedule, all fluids on your vehicle should be changed regularly, the interval depending largely on your driving habits. Despite manufacturer’s maintenance schedules that may not even mention a brake flush or may claim that the anti-freeze will be good for 5 years, experience tells us that 2 year / 50,000 kilometer intervals is a good benchmark for coolant, brake, transmission, power steering and differential fluid exchanges. Engine oil and filter should be changed every 4 months or 5,000 kilometers, whichever occurs first, with few exceptions.

Anti-freeze serves to protect the engine from overheating as much as to prevent the coolant from freezing in the winter. Unfortunately, coolant becomes acidic over time and may cause corrosion to sealing surfaces, accelerate wear to the water pump and create restrictions in the radiator. Some new long-life coolants may not require changing for 5 years or 100,000 kilometers under ideal conditions, but they appear to be susceptible to sludge formation under certain conditions, not all of which may be known at this time. In some cases, this will result in the need to perform a major coolant flush procedure, and involves replacing other components in order to restore cooling system functionality.

Automatic transmission fluid has a tough job! It has to lubricate hundreds of moving parts in the transmission, provide hydraulic pressure to actuate clutches, absorb impurities created within the confines of the transmission and perform under severe stress and temperature variations. Over time, the fluid becomes oxidized, saturated with impurities and loses its ability to adequately lubricate and clean. If not replaced in time, transmission wear will accelerate, causing premature failure and major expense.

Power steering fluid does much the same job as transmission fluid and is very similar in appearance and specifications, although it doesn’t have quite as stressful a time of it as transmission fluid does. Still, wear and tear inside the typical power steering rack and pinion used on most modern automobiles will deteriorate the fluid over time to the point where it loses its ability to lubricate and absorb impurities. The resulting wear in the steering gear may result in intermittent loss of power assist. Dirt in the fluid may cause pressure variations in the pump, which could in turn result in leaks or component failure.

Brake fluid must maintain hydraulic pressure throughout the brake system when the brakes are applied. At the same time, it must be able to withstand the extreme heat created by the friction required to slow the wheels. Brake fluid, by nature, is hygroscopic, meaning that it absorbs moisture. Even in a properly closed system, small traces of moisture somehow manage to deteriorate the fluid. Excess contamination will reduce the boiling point of the fluid to unsafe levels, as well as make it corrosive. Long before the fluid would become unsafe, it would have become corrosive enough to cause irreversible damage to components such as wheel cylinders, calipers and master cylinder.

Proper fluid exchange, which includes flushing out all or most of the old fluid, not only helps your vehicle run better, longer; it really can save dollars in the long run.

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We would like to thank Art French from AML Auto Service for contributing this article.