Are the fluids in your vehicle maintenance free?

Quick facts

  • Transmission fluid oxidizes and loses its protective properties over time, even in "lifetime fill" units
  • Brake fluid is hygroscopic, meaning it absorbs moisture from the air and lowers its boiling point over time
  • Coolant should be tested for pH and freeze protection level every 2 years
  • Power steering fluid breaks down and can damage pump seals if left unchanged indefinitely

This article is the 2nd one on whether today’s vehicles are really maintenance free.  We were talking about engine oil, it is interesting but a simple oil change is one of the best returns on investment that you can have performed on your vehicle. By keeping the engine oil clean no matter what the service interval is, it helps maintain and improve your vehicles value, longevity, safety and reliability. Engine oil is just one of the many fluids in your vehicle.  Engine oil and transmission fluid are the fluids for the 2 most important and most expensive components of your vehicle, the engine and transmission.

If you look at the transmission fluid the automotive industry standard is to replace the fluid at minimum every 30,000 miles.  If you talk to a transmission specialist who spends 100% of their time repairing and overhauling transmissions that have failed, they are going to tell you they should be serviced closer to every 20,000 miles.  Transmission fluid is full of detergent and like engine oil it is designed to clean, cool and lubricate.  Dirty fluid has suspended particulate in it that can be abrasive and accelerate the wear of the transmission.

Coolant is designed to keep the engine cool.  It provides a higher boiling point and a lower freezing point as well as lubricating the engine water pump and has corrosion inhibitors to help reduce corrosion in the coolant passages of the engine.  Coolant for your vehicle, in our climate should be kept at the freeze protection level of – 32 degrees fahrenheit.  Coolant has a ph balance between alkaline and acid, if it is allowed to age and become acidic it can actually do damage.  The acidity can eat away at hoses, gaskets even metal overtime.  Keeping coolant changed regularly, can keep it clean, at the proper protection level and at the proper ph balance for the best results.  The industry standard is to flush the coolant every 2 years or 30,000 miles to keep it in the best shape.

In out next article we will discuss if maintenance free vehicles really exist.  Happy Motoring!

Frequently asked questions

Common questions

My owner's manual says the transmission fluid is lifetime fill: do I really need to change it?

"Lifetime" means the expected life of the transmission under ideal conditions, not necessarily the life of the vehicle. Many transmission failures in high-mileage vehicles with "lifetime" fluid are partially attributable to degraded fluid. Most transmission specialists recommend a fluid exchange every 30,000 to 60,000 miles regardless of what the manual says. The cost of a fluid change is a fraction of a transmission rebuild.

How often should brake fluid be changed?

Most manufacturers recommend every 2 years, and many technicians agree. Brake fluid absorbs moisture over time, which lowers its boiling point and can cause vapor lock during hard braking. In Oregon's wet climate, brake fluid absorbs moisture faster than in dry regions. A simple test with a brake fluid tester strip checks moisture content in seconds.

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