Q: On my vehicle's dashboard I have a range setting that tells me how far I can go on a full tank of gas. For the past two years, range with summer gas has been 366 miles, winter gas 336 miles. As you can see, there is a 30-mile difference. Lately I'm only getting 349 miles per tank when I should be getting 366 miles per tank. At the end of April I got 367 miles per tank in Missouri. But then it immediately dropped to 349 miles and has stayed at 349 miles ever since. Did the gas companies change to a third type of gas? Do we now have three different grades of gas for summer, winter and now spring?

T.K., Elgin, Ill.

A: There are actually several blends of gasoline depending on the season and the locale. Plus some marketers, such as Sunoco, have more than the traditional three grades: regular, midgrade and premium. Even the grades may have different octane ratings depending on location. In the high plains states like Wyoming and Utah, for instance, gasoline has lower octane than in the Midwest plains states like Illinois and Indiana. Keep in mind that gasoline is actually a mixture of chemicals including things like benzene and other relatively volatile hydrocarbons. As they say, your mileage may vary.

Q: I have a 2008 Ford F-150 with a steering problem. I have about an inch of play before the wheel actually turns. When turning the wheel it goes nice and easy until it becomes difficult and then it goes back to easy turning again. It happens either way you turn the wheel, right or left. It turns easy, then hard, then easy. Is this a power steering pump or rack-and-pinion problem?

D.O., Hingham, Mass.

A: It is probably neither the power steering pump nor steering gear. It is most likely a worn intermediate steering shaft. There are two universal joints that are prone to wear, especially in Snow Belt states. The U-joints corrode and wear. The wear causes the looseness that you initially feel and then the U-joints bind, making it difficult to turn the steering wheel further. The shaft is not extremely expensive, especially compared with the other parts you mentioned.

Q: I recently bought new tires and want them to last. There are many products to shine and protect tires from UV radiation, but the manufacturer's warranty is void if I use a tire dressing containing petroleum distillates. What alternatives do you suggest?

G.J., Des Plaines, Ill.

A: Look at the label. Many dressings are now water-based and will cause no harm.

Q: I have a 2016 Nissan Rogue. It has a "black box" recording many driving statistics. How long is data stored? How can an owner get access to the data and print reports?

R.B., Schaumburg, Ill.

A: Black box is the common name for the event data recorder. It records information for only a few minutes and overwrites itself continuously on an electronically erasable programmable read-only memory. It only saves data in the event of a crash. Some of the information it records are vehicle speed at the time of impact, whether the brakes are mashed, whether the seat belts were buckled, if the airbags deployed and so on. The information is not readily available to the car owner.

Bob Weber is a writer and mechanic who became an ASE-certified Master Automobile Technician in 1976. He maintains this status by seeking certification every five years. Weber's work appears in professional trade magazines and other consumer publications. His writing also appears in automotive trade publications, Consumer Guide and Consumers Digest Send automotive questions along with name and town to motormouth.tribverizon.net.