Q: While searching the Web to try and figure out what's wrong with my '03 Subaru Baja's brakes, I came across your article on braking issues and wonder if you could help me. Under cold or wet conditions my brakes buzz and vibrate and affect stopping ability. I suspect it's an ABS issue as it only occurs when there's some sort of loss of traction to one or two wheels. Should I bleed the brakes or do you think it's a greater issue?
A: I'm not sure there is an issue. You've described exactly what happens when the ABS engages. Antilock brake systems consist of sensors that monitor the rotational speed of each wheel. Under braking, the ABS control module compares the rotational speeds and if one or more wheels are slowing more rapidly than others, recognizes this as impending brake lockup. The module cycles electromagnetic "dump" valves open/closed rapidly to release just enough hydraulic pressure to keep the wheels rotating at the edge of lockup.
Remember the "good old days" before ABS? Drivers were advised to pump the brake pedal as rapidly as possible when the wheels locked up in slippery conditions. ABS does this for you far faster and more effectively. Its cyclic rate is exponentially higher and it releases just enough hydraulic pressure to only the wheels that are locking up. By keeping all the wheels/tires at the edge of lockup, the ABS maximizes the stopping power of the vehicle in those conditions. The italics are to emphasize that ABS cannot overcome the laws of physics, meaning the car will decelerate only as well as the traction between tire and road surface allows.
In your case, it would appear that available traction — "cold or wet conditions" — are affecting stopping power, not the ABS system. In fact, the ABS is likely maximizing stopping power in this low-traction scenario.
Should you bleed the brakes? I suggest — as do many carmakers today — that the brake fluid be exchanged every one to two years through brake bleeding to remove any moisture-contaminated fluid that could degrade brake performance.
Even just emptying and refilling the brake fluid master cylinder reservoir once per year with a turkey baster-type siphoning device — without bleeding the brakes — exchanges a high percentage of old fluid with fresh fluid. This isn't as good as fully bleeding the brakes, but it's certainly better than doing nothing.
Q: I have an old car in storage and I'm concerned about the level of antifreeze protection it may have with the very cold weather. I tested it and three balls floated, meaning it is good to 10-below. Should I worry about freezing and potential engine block cracking? If it gets to this temperature or below, should I add a magnetic engine block heater? As it is stored now it would be difficult to try to drain and increase the coolant protection.
A: Assuming your vehicle is stored in some sort of structure, the unheated air will usually be roughly 10 degrees above the outdoor temperature. Moreover, a car in air below minus-10 degrees would have to be subjected to that cold for some time before any solid freezing would occur.
Yes, any type of coolant heating system, even an incandescent light bulb or heat lamp safely placed under the hood, would add additional protection. You could also increase the antifreeze protection level by simply siphoning a half-gallon directly from the radiator and topping it up with 100 percent antifreeze.
Q: I have a 2008 Mercedes C300 with only 5,000 miles. Last time I had the oil changed, around 3,500 miles, was 18 months ago. Do you think I should change the oil now? Does time also matter?
A: Change the oil and filter once per year. Consider it cheap insurance. Time does matter in the sense that oil, as a petroleum product, does oxidize and collect moisture over time. This produces sludge and varnish that are detrimental to engines.