Which Transmission Fluid to use?

I have a 1999 Hyundai Elantra GLS Sedan, automatic transmission. I plan on doing a Transmission Fluid change. I asked someone at the auto part store which transmission fluid to use and they told me ATF+3.
When I got home I checked out my owners manual and it lists 3 types:
Hyundai ATF SP-11
Autran MMSP-11
Diamond ATF SP-11

Which 1 do I use? Is ATF+3 any better?

If someone could post the procedure in performing a transmission fluid change for my car I would really appreciate it. I understand there is a drain plug, when turned will drain all the fluid. So all I need to do is refill with new transmission fluid? Someone told me that the filter and gasket only need to be replaced if I have a leak. Is this true?

Thanks again for any input.

I would reccomend doing a drain and fill. Which will take abouit 3-4 quarts. Only use Hyundai sp III! A good suggestion is to drain it in a container (like a milk jug) and mark how full it is with a sharpie. pour out the old fluid and clean the container and refill it with new fluid. Now you have replaced the exact same amount of fluid. But you should still check your fluid level. This is done running, e- brake on, and transmission in neutral. Also A helpful hint is to check your level as desrcibed previously before draining just to know where you are starting at. Good luck and keep up the preventive maintenance.

Thank you so much for responding! I will definitely take your advice. Quick question though. You mention I will need to refill about 3 - 4 quarts of automatic transmission fluid. The owners manual states that it holds 7 quarts. I wouldn't want to buy only 4 quarts only to find out half way through that I dont have enough and get stuck without extra. Perhaps only 3 - 4 quarts will only drain out because I am not touching the filter and gasket? I think I'll just buy 7 quarts to be safe.

Thanks

Thank you so much for responding! I will definitely take your advice. Quick question though. You mention I will need to refill about 3 - 4 quarts of automatic transmission fluid. The owners manual states that it holds 7 quarts. I wouldn't want to buy only 4 quarts only to find out half way through that I dont have enough and get stuck without extra. Perhaps only 3 - 4 quarts will only drain out because I am not touching the filter and gasket? I think I'll just buy 7 quarts to be safe.

Thanks

There are a few quarts in the torque converter, thats where the rest of the fluid is. Only way you are going to get that fluid out is to have someone flush it out.