97 Honda Civic HX bad MPG

I bought a 97 Civic HX 6 months ago and have put about 8000 highway miles
on it. I have only replaced the spark plugs when I first got it and got
close to 40 MPG. It has 88000 miles. In the last 1000 miles it is down
to around 33MPG (under same driving conditions). What should I look to
replace to improve the gas mileage?

 

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It's colder out. Don't idle it to warm it up, (check the manual) and
check / replace the PCV.

'Curly'

 

I don't warm it up, just get in and drive. What about the O2 sensors?
I'll check the PCV first. It's cheaper that O2 sensors. Any other
suggestions appreciated.

Thanks.

 

My 95 Civic Coupe gets crap MPG as well. It's only done 45,000 miles.
I've tried driving gently, keeping the RPM under 3,000, using fully
synthetic oil, removing everything in the boot including the tool kit
and spare tyre and even inflating all the tyres to 35psi. Still gets
around 34mpg.

Whats the PCV?

 

Do not switch to synthetic oil, your car is use to the original lube! STay
away from synthetic! It has too many detergents in it. And your engine has
gotten use to the regular oil.
A very important thing is your air filter! Change it to a K&N replacable air
filter, to give you better accelleration and more horsepower. With the fuel
loss, I wouldn't take off to fast, or rev your engine too high! You can get
very good prices at auto parts extra. I bought mine for 54$ plus tax.
canadian tire wanted $78, and some other import shops, and auto performance
shops wanted $118

Usually honda's don't reccomend using a fuel cleaner, stabilizer or octane
booster, but I would look into getting an STP fuel and carborator cleaner,
usually they're about 3$ at wallmart, and you put it in your gas tank when
it is on empty, then fillup your gas tank.
Make sure your tires are filled at the proper air pressure. If it is over,
or under it will use more gas. Same goes with alignment, get it checked!
Don't carry a heavy load in the trunk, this uses alot more gas. Depending on
your motor, the faster you drive, the more gas you burn!