Battery

00' GT, 3800, 45500k

I am looking at possibly replacing my OEM Delco battery this fall. I live in the harsh climate of Nebraska, so a good battery is required :).

1) How long do the OEM batteries last?
2) Would I be able to do a battery load test DIY?
3) If so, how would one do it, what tools are required and what are the
results that should tell me whether I should/shouldn't replace the
battery?
4) If I do need to replace it, what brand battery tends to work better
than others?


Thanks for all your help again.