Verified answer

Go to Honda and purchase Honda's Manual Transmission Fluid. Otherwise the alternative is 10W40 motor oil believe it or not. Don't use synthetic motor oil though.

I've used regular engine oil 5W30 twice for my manual transmission; works fine.

2 quarts will cover the requirements, you can either pour in the amount specified in your Honda Civic owner's manual, or monitor the oil level through the transmission oil fill plug.

Good luck!

DO not use engine oil. Your local honda dealer should have the correct fluid at the parts department. Your owners manual should list the capacity of the transmission. If you do not have your manual, I believe you can downlaod from the honda owners link site.