Doing damage by coasting down hills?

Q. Aside from the sticker shock, did I do any harm to my Ford Freestyle by filling the tank full with premium gas (ouch!) instead of regular gas as I normally do? Our family also uses a second car that only takes premium gas and I wasn’t paying attention!

A. There are very few cases that using premium fuel in a car that doesn’t require it will cause any harm. So you did nothing more than cost yourself a couple of dollars more. If you filled up with diesel or E-85 ethanol gas, that would be a different story.

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Q. I am a regular reader of the Car Doctor column and AAA Horizons and would like to get some info on my 2004 Toyota Matrix. The car has only 57,000 miles on it and is doing quite well. On the car’s last check up, the mechanic said that my real axle seals are leaking and need to be replaced. He gave me a quote of $725.00 for the full job including alignment and labor and parts. My question is, does this cost sound in the right ball park or should I look around for another price? He said they are not leaking badly so what do you think I should do? One more thing, I am looking for a new car and looking at a Prius. What do you think? Thank you and keep up the great columns.

A. If the seals are leaking they are certainly not going to get better by themselves. If there is minor seepage this may be an issue that requires no more than monitoring of the situation. The typical labor time to replace front axle seals is three hours plus parts. If it is rear axle seals, it will take about six hours to replace the seals. At $100 an hour the $725.00 could be average, if it is the rear axle seals that need replacement. Regarding the Prius, I believe it is one of the better hybrids on the market. In addition to the great gas mileage, I find the hatchback design to be very practical.

Q. I own a Toyota Prius that I bought new in 2006. It has been a great car and trouble free and has 135,000 miles on the odometer. I get 46 to 52 miles per gallon depending on the terrain and weather conditions. I have discovered that by putting it in neutral and coasting downhill and grades that I can easily increase the gas mileage another 10 miles per gallon. My question is am I doing damage to the transmission? By the way what do you think of the Prius?

A. I don’t think shifting into neutral is a good idea, in fact your car’s owner’s manual may warn against it. A better technique is to anticipate hills and gently accelerate to keep a constant speed. Other times, lift off of the accelerator to the point the car starts to coast or glide. In my opinion, this is a much safer technique while still maximizing fuel economy. The Prius in my opinion is still the best affordable hybrid sold today. It offers the best combination of mileage, dependability and versatility.

Q. I usually buy name brand oil and filters for my car, but recently I was in a large department store and notices they have their own brand of oil and filters. What do you think of using this generic-store brand oil and filters?

A. I will admit I tend to be a brand name user when it comes to oil and oil filters. That said as big as mass merchandisers are they don’t own refineries, they just have oil companies put products in containers with their name on it. As long as the oil and filters meet the manufacturers specification it should work just fine and may be a bargain to boot.