SK wrote:

> Guys
>
> Purchased a used Automatic '97 Honda Civic EX 4 months ago with just
> 56K miles on it. I drive about 1500 miles/month - 90% highway miles
> (60-75 mph). I do oil changes promptly at 3k miles. Last week my car
> hit 60K miles and I changed the Spark Plugs (Firestone replaced with
> Bosch Platinum plugs). they even said that the wires, rotor and
> distribution cap are good. Tires and Brakes are good. Before I changed
> the Spark plugs I used to get 28mpg and now i am getting only 22mpg. I
> was expecting it to hit atleast 30mpg. I am very concerned now. Can
> anyone help me understand what the problem is?
>
> One of my friend suggested that I can change the Air filter - Planning
> to do that soon. Should I replace the transmission fluid, fuel filter
> or anything else? I use 87octane either at Wawa or Shell.
>
> Thanks in advance for your time
> SK

Changing the air filter might help a bit. But I think the biggest problem
is the Bosch spark plugs. Get rid of those and get OEM plugs by NGK or ND.