Is it true that it is good for a car to fill it up with higher grade gas once in a while? I usually fill up at Shell, and there is 87, 89 and 91 kinds of gas, with 87 being the cheapeast and 91 being the most expensive. I usually get 87. However, I heard that if you own a car and want it to last longer, it is beneficial to fill it up with the most expensive gas, to "clean the engine". Is that true? If so, what is the explanation behind it? I drive a 2002 Kia Rio, if that makes any difference.
how much money can I save by turning off air-conditioning when I drive? [more inside]