Q: What's with this new eco-friendly gas blend with the yellow handle? Will it harm a non-flex-fuel engine? It's as much as 50 cents cheaper.

A: E85 (or flex fuel) is a term that refers to ethanol-gasoline blends containing 51-83% ethanol, depending on geography and season. Other than lower miles per gallon, motorists driving flex-fuel vehicles will see little difference when using E85 vs. gasoline. Depending on the actual ethanol content, E85 has less energy per gallon than gasoline to varying degrees (fuel economy decreases as the ethanol content increases). Don't put it in cars that are not designed to run on flex fuel.

Noise a bad sign

Q: I recently had an oil change on my 2007 Nissan Altima, after which my longtime mechanic said I should do both front and rear brakes. The car stops fine with no squeaking or grinding noise. Is there any way to tell if I need new brakes without getting a second opinion? If he shows me the pads on the upcoming oil change, what am I checking for?

A: Check for the thickness of the friction material — the stuff that contacts the brake rotors. I would say that about ⅛ inch of friction material is about the limit. Your mechanic probably can eyeball them, but measuring with a caliper is the professional approach. If your pads are approaching that, I would replace them. Once you hear noise, you've waited too long.

Frustrating ritual

Q: When I went to get an emissions test on my 2014 Honda Civic, I was told that a monitor was not ready (the catalyst monitor was the culprit). I eventually discovered that my manual has the instructions for a "drive cycle" that must be completed to get the monitors ready. I did the magical drive cycle, but it did not work. I think it might be because I was driving at highway speeds and not the "50 to 60 mph" specified. Why is the cycle to get the monitors ready so different from typical driving? Who lets their car idle for 20 seconds, then revs up the engine to 2,000 rpm for three minutes, then idles for 20 seconds, then gets on the highway and maintains a speed that will anger other drivers for 20 minutes?

A: The drive cycle was created in a laboratory established by the EPA long ago. You really need to follow the drive cycle properly, and high speed is not one of the criteria.

Bob Weber is a writer, mechanic and ASE-certified Master Automobile Technician. His writing has appeared in automotive trade publications, Consumer Guide and Consumers Digest. Send automotive questions along with name and town to motormouth.tribune@gmail.com.