Besides a Optima Red Top. My experience with the Red Top on my wife's IS300 tells me that they are not the same quality they once were.

 

Optimas have been crap for a while. I just put in a Batteries Plus AGM, sealed so no water/corrosion issues. 3 or 4 year warranty, cant remember but they have 2 different types for the G37.

 

Tips for getting it out and back in, as it looks like a PITA. Does the surrounding trim need to be removed?

 

That's easy. Remove the battery cover, then remove all the plastic push pins that hold that trim piece in place (use a small screw driver to pop up the center pin a bit then grab the outer piece with your fingers and pull straight up). If you have to remove the plastic cowl section I believe it comes out with 1 push pin hidden on the fender seam and a clip holding it to the drivers side section which is easy to see how it comes undone.

 

Well interstate and optima are same company. You'll get a bad battery from and manufacturer. Last redtop optima lasted 6 years cause car was sold with it.