Your brake fluid flush should be changed every 72,000 km

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This article was published 27/04/2018 (3039 days ago), so information in it may no longer be current.

Question: I own a 2015 GMC Terrain, four-cylinder with 52,682 kilometres. This vehicle was purchased new in October 2014. I have recently had my Terrain in for servicing at the local GM dealership. They indicated the following services were required: fuel injection service (every two years or 32,000 km), brake fluid flush (two years or 48,000 km) and transmission flush (two years or 72,000 km).

I declined the services. I found them to be excessive. In my past vehicles I drove for six years to 110,000 km and never did these services and the vehicles worked fine. What’s your take on this?

— Jeff

Answer: These services sound excessive to me too, given the low mileage and age of the vehicle. Modern vehicles are very reliable. The only service work recommended by the dealership I feel is reasonable is the brake fluid flush.

I looked up the maintenance schedule in the owner’s manual for your vehicle. There are two service maintenance schedules — normal use and severe service. If you drive short trips all the time, haul heavy loads, tow a trailer, operate at very high speeds, drive off-road or up steep hills a lot, then you would qualify for the severe service maintenance schedule — but most of us can use the normal maintenance schedule as a guideline for having service work done.

According to the normal maintenance schedule, brake fluid should be changed (flushed) every 72,000 km or every three years.

Your vehicle is three years old and changing brake fluid makes economical sense if you are keeping the vehicle. Brake fluid degrades with time. It absorbs moisture from air which can enter past seals or when the system is opened. Also, copper molecules migrate from metal parts in the brake system over time and contaminate the brake fluid.

The contaminated fluid will corrode expensive parts such as master cylinders and ABS and traction control hydraulic units. It is much cheaper to flush the fluid every three years than replace expensive hydraulic parts. There is no mention of changing transmission oil in the normal maintenance schedule.

In the severe service schedule, it is recommended transmission oil be changed every 72,000 km, and the AWD transfer case fluid should be changed at the same time. Your vehicle isn’t at that mileage yet, even if they were looking at the severe service schedule. There is no mention of fuel injection service and you shouldn’t need it if the vehicle is running fine. You did the right thing to turn down the service and check further. Now you can have the brake fluid flushed knowing it is actually reasonable.

james.kerr@sasktel.net