I don't have the owner's manual.

I am going to change the oil on my gf's 1999 Honda Civic LX. I've done it on my Integra before, but I'm not sure if the setup is the same.
Is the oil filter located near the firewall on the driver's side?
How many quarts of motor oil will I need?

My last question -- her maintenance light required came on. Is there a switch to reset this light? I assume it comes on every certain number of miles and that there's nothing really that needs to be serviced. Correct? (this is my experience with my Integra)

 

yes same location for oil filter.
its a little less than 4 quarts i THINK.
and not sure on the maintance light. i know there is a switch to reset it but no idea where. check under/behind the dash.

 

It's the same as an integra, you might not need all 4 qts. I'd do 3 1/2 quarts, let it settle and check the dipstick. About the service light, that's just another ploy for honda to make money.

 

The maint. light can be reset by just sticking a key into the slot adjacent to the maint. light. That will reset it.

If you're changing the oil and the filter, replace it with 3.6-3.8qts... whatever it takes to reach the upper mark on the dipstick.