In the car business, there are several automotive systems that use oil-based fluids for "functional purposes." This means the fluids are a part of an automotive system and perform such operations such as hydraulic movement and lubrication. A non-functional fluid would be something like the windshield cleaning fluid in your windshield washer system. A windshield washer system uses the fluid just as an agent to squirt on your windshield. In this article, we will look at the manufacturer's recommended change intervals of functional fluids.

POWER STEERING FLUID The suggested change interval for today's power steering fluids is 60,000-100,000 miles. Not long ago, there was no suggested change interval for power steering fluid but things are different today. Wider wheel and tire packages are putting more strain on power steering systems and more strain on the pump and rack means more heat is generated. This heat can degrade the power steering fluid and eventually damage the seals and internal surfaces of the pump and rack. Hence most manufacturers now have recommended change intervals for their power steering systems.

Note: Our subject matter experts for this article, Brookfield Chrysler Dodge Jeep Ram of Benton Harbor, MI, remind us that there's an old saying: There is no such thing as a universal power steering fluid. Different manufacturers use different formulations that are matched to the seals in the system. If you add the wrong fluid to your car's power steering pump reservoir, you may end up ruining the seals. Before you add fluid, check in your driver's manual for the correct fluid type, or with your local brand dealer.

BRAKE FLUID The suggested change interval for today's brake fluids varies from every 100,000 miles to 150,000 miles. It depends on the manufacturer. In the old days, brake fluid was rarely changed but things are different today. Today, ABS, ESC and traction control have become standard on most vehicles. When these systems activate to either release or lock a wheel, the hydraulic control unit's valves can be hard on the brake fluid. The high pressure and force exerted on the fluid can degrade not only the fluid but also the additive package that was added. When the additive package changes due to water contamination and wear and tear, the viscosity can change and the brake fluid needs to be changed at that point.

TRANSMISSION FLUID The suggested change interval for today's power steering fluids is 80,000-120,000 miles. In the past, some manufacturers suggested that the fluid would be replaced only when the customer detected a change in transmission shifting. Today, modern transmissions are "smarter" and can mask worn fluid by changing shift points and line pressures automatically. However, it is still possible for transmission fluid to wear out. The original fluid's viscosity changes and depleted friction modifiers can damage the clutches and bands. This can ruin a transmission so it is smart to change both your transmissions filter and fluid according to the manufacturers schedule.

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