6.5 liters
6
According to my manual the 5.3 (Engine VIN "T"), including the filter, has a 6 quart capacity. I just changed my oil and put 5 quarts in and when I checked the dipstick the oil level was 3/4 of the way up the hatchmarked area. Haven't driven it yet.
4L/4.2Q
Because 2t burns cleaner than 4t.
The engine oil capacity for a 1999 Honda Civic is 3.5 quarts. (Just in case you meant transmission fluid - since you mentioned it's an automatic - the A/T fluid capacity is 3.0 quarts. Note, if you have a GX or HX model with a Continuously Variable Transmission, it will take 4.0 quarts of Honda CVT fluid).
5 quarts
gas engine? engine oil.... Diesel engine? rotella t 15-40W
About 2, t 2.5, gallons.
Use 4 quarts full synthetic 10w30.
the best oil for a diesel is rotella t 15w 40.
Locate the engine's oil pressure sensor, remove it and add T-branch between. Then attach the oil-gauge's/unit's oil-line to the T-branch.
3.1 Quarts....Honda Oil GN4 10w-40w or Shell Rotella T Synthetic.