Brake fluid color can be a tip-off

Q I have been told by a car dealer as well as an independent shop that I need new brake fluid at 70,000 miles on my Malibu because the "color is bad." Is this a scam? I have never heard of this before, and my owner's manual does not talk about it.

A It's not a scam. Because brake fluid absorbs moisture from air, I suggest bleeding the brakes to flush and refill the system with fresh brake fluid every two years, whether or not your owner's manual recommends it. Fresh brake fluid reduces corrosion in the brake system, including expensive anti-lock brake actuators and control units.

It's all about the PM -- preventive maintenance.

Q My dad bought a used 2005 Chevy Impala. It made no noise when he bought it, but he took it back to the dealer to tighten the emergency brake because he tows a boat and did not want the car to slip at the lake. Then it started to clunk in the back. The tires were bad so he had new tires put on. It still clunked and made a grinding noise during braking. We replaced the left rear axle assembly, but it still makes the noise. Is it a warped rotor?

A I'd be more suspicious of the parking brake mechanism. On this vehicle, the parking brake system consists of a small set of brake shoes that are applied against the inside of the "hat" section of the brake rotor. In other words, it's a completely stand-alone mechanical system that is not dependent upon the hydraulic disc brakes.

I suspect the parking brake was adjusted a bit too tight, or the mechanism inside the rotor is sticking or binding because of rust. The next step would be to inspect, disassemble, clean and reinstall the rear parking-brake components.

As with any vehicle operated on Minnesota's salt-encrusted roads, either use the parking brake every time the vehicle is parked to keep it free and functional, or don't use it at all.

I have replaced the thermostat twice (with different types) and drained and refilled the cooling system with new antifreeze, but this did not help. Any help would be appreciated because it is getting colder outside every day.

A Did you try a two-stage thermostat? A "jiggle-valve" style thermostat allows a small amount of circulation before the thermostat starts to open to aid the warm-up process. If the thermostat is installed backward or oriented in the housing incorrectly, it can cause a slow warm-up.

Did you fully "bleed" the cooling system when you refilled it with coolant? Chrysler outlines a specific procedure using a special funnel to fill the system while the bleed screw on the thermostat housing is open. It often takes a couple of fill/bleed attempts to fully purge the system of air.