I stopped messing with car batteries years ago. In good faith I bought a yellow top Optima battery but it failed in less than 12 months and the manufacturer wouldn't honour the warranty because I had a high powered stereo in my car.
So now I only use "standard" batteries and replace them as needed. You could try adding rejuvenation etc. but IME it's best just to bite the bullet and buy a new one.
I use this to test car batteries... If it fails the test it gets replaced.
- Search for "Solar B47" on Google.
and Kent's excellent video on how to use one.