Q: What on earth is the rationale for gas stations to list their prices to include 0.9 cents at the end? When gas was 29 cents a gallon (I remember paying 19.9 in Texas in 1968) the fractional cent might have made sense. Now it doesn’t, so why keep implying that $2.39.9 a gallon is not essentially the same as $2.40?
— M.W., Glen Ellyn
A: That fraction of a penny goes back a lot further than 1968. Try 1918 or thereabouts, when a penny went a lot further, too. Around the time of the Great Depression, the federal government tacked a 1.5 cents per gallon tax on the stuff. Since times were already tough enough, gasoline retailers used the tried-and-true marketing trick of using the 0.9 instead of whole cents and it has been thus ever since.
Q: I have a 2014 Subaru Outback. Our low-oil light comes on about 1,000 to 2,000 miles prior to a scheduled oil change. The dealership casually dismisses the finding as just an indication that the oil needs to be changed. There is no oil spot in our garage where we park. The dealership has mentioned needing to do an oil consumption test. What exactly does this mean and what exactly does it uncover?
— B.A., Chicago
A: An oil consumption test is simply checking the dipstick to determine at what mileage the engine is down a quart. It is done at scheduled intervals, usually every 1,000 miles. All engines use some oil, otherwise certain components such as valves will seize. If your engine is using less than one quart every 1,000 miles, car makers consider this normal, even though car owners disagree.
Q: Perhaps this is a silly question. It looks as though my current set of tires will need replacement in about a year based upon how I drive. So, I started thinking about which tire is better for my 2014 Nissan Quest. I have no idea how run-flat tires would feel while driving with a flat tire. I also have yet to research if such a run-flat tire is even appropriate for my vehicle. My thinking is that I’m better off with the normal type tire while always carrying a can of Fix-a-Flat as I do now. Not only is a can of that stuff less expensive, but why buy expensive tires?
— D.S., La Porte, Ind.
A: Run-flat tires provide a margin of safety to drive to a safe place and have the flat changed. You will feel the difference when this happens, but it is nowhere as squirrelly as a regular flat tire. Carmakers are gradually doing away with spare tires as well as run-flats in favor of sealer-and-inflater kits that save space and weight.
Q: Love your columns and have been a reader for many, many years. My question is: I purchased my dream vehicle last year, a 2015 BMW X3 turbo diesel. Love it and it is the best vehicle I’ve owned. I purchase the correct diesel fuel required, but I was wondering if purchasing diesel from Top Tier fuel stations is better than diesel from Sam’s Club or other discount clubs?
— E.S., Gilbert, Ariz.
A: The Top Tier designation only applies to gasoline. We are aware of no similar designation for diesel fuel.
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